Organized Crime in Philadelphia (with Gary W. Potter), Delaware Valley Crime Commission, Philadelphia, January 1986


The Mob and the Mafia (with Gary W. Potter), Italian-American Media Institute, New York, November 1986


 Revolutions in Criminological Theory, Criminology Department at the University of Melbourne, Australia, June 1988.


 Serial Murder in the Contemporary United States, Sociology Department, University of Southern Maine, Portland, ME, April 13, 1989.


In May 1994, I was an invited participant in a Liberty Fund Colloquium held at Delavan, Wisconsin, on the theme of Liberty, the Individual and the Family.


Teaching Religion and Teaching About Religion, West Virginia University, Morgantown, WV, April 1996.


The Far Right in Philadelphia Politics 1920-1960, History Department, St. Joseph’s University, Philadelphia, PA, April 1997


Welsh Immigration to the United States, Welsh Society of Philadelphia, October 1998.


The Wildest Frontier: The Electronic Market in Child Pornography, University of California, Davis, lecture in series on Disordering Globalization, February, 2000.


Nothing New Under the Sun: A Historical Perspective on Social Problems, School of Criminology and Criminal Justice, Florida State University, Tallahassee, November 2000.


Child Pornography Online, Sociology Department, Wellesley College, MA., February 2001.


The Politics of Ecstasy, Elon College, North Carolina, April 2001.


Child Abuse and Moral Panics, Keynote address for conference on childhood sexuality held at the Kinsey Institute, Bloomington, IN, May 2001.


Futures of American Religion, Netherlands American Studies Association. Middelburg, Netherlands, June 2001.


Globalization and the Transformation of Christianity, Foreign Policy Research Institute, Philadelphia, PA, September 2001.


The Competition for Converts between Christianity and Islam, Harvard Academy, Seminar on Globalization and Culture, Harvard University, March 2002.


Participant in panel at conference on The Bible and the Ballot: Evangelicals and Third World Democracy, Potomac, Maryland, June 2002


The New Christianity and the Future of Global Politics: Toward an Understanding of Religion and Political Conflict, meeting organized by Ethics and Public Policy Center, Key West, FL, December 2002.


Islam in The American Experience, History Day lecture, Foreign Policy Research Institute, Bryn Mawr, PA, May 2003. This paper was circulated in FPRI’s Watch on the West 4(4)(2003). It was also reprinted in The WorldPaper.


Invited speaker and panelist at Religious Freedom: The Missing Dimension of Security, Brandywine Forum 2003, held at Eastern University, St. Davids, PA, May, 2003.


The Church’s Role in Africa, Trinity National Leadership Round Table, Washington DC, June 2003.


Islam and Christianity: Cooperation and Conflict, Witherspoon Fellowship, Washington DC, July 2003.


Faith and Secularism in the US and Worldwide, keynote address, Conference on Faith and Secularism, Princeton University, October 2003.


Apocalyptic Terrorism in the United States, New York University, October 2003.


My book The Next Christendom was the subject of a panel discussion at the Academy of American Religion meeting in Atlanta, GA, November 2003. It was also the subject of a separate panel at the Evangelical Theological Society, also meeting in Atlanta. I participated in both events.


In February 2004, I was the William Belden Noble lecturer at Harvard University, delivering three lectures on the theme of Emerging Christianities


Ethiopia Shall Lift Up Her Hands, Society of Pentecostal Studies, Milwaukee, WI, March 2004.


In March 2004, I gave the Albert Cardinal Meyer lectures at the University of St. Mary of the Lake (Mundelein Seminary), in Illinois.


In April 2004, I gave the keynote lecture at the conference on The Future of the Church in a Globalized World, held at the Center for Christian Study, in Charlottesville, VA.


Truthful Reporting on Religion and Culture, Gegrapha Conference on Journalism in Asia, held at Subic Bay, Philippines, November 2004.


Colliding Diasporas: Immigrant Christianity in the New Europe, Institute of European Studies, University of California, Berkeley, December 2004.


The Da Vinci Code and the Quest for Hidden Gospels, Missouri Baptist University, St Louis, MO, June 2005.


Colliding Diasporas: How Global Christianity and Global Islam Encounter Each Other In Europe, Series on Religion, Political Economy and Society Seminar, Weatherhead Center for International Affairs, Harvard University, December 2005.


Informed Sources: The Construction of Terrorism, University of Ottawa, March 2006.


The Global Context, Conference on The New Evangelization, Sacred Heart Major Seminary, Detroit, March 2006.


Decade of Nightmares, Carnegie Institute on Ethics and International Affairs, New York City, April 2006; I also spoke on this topic at the Cooper Union, New York City.


In May 2006, I was the Commencement speaker for Trinity Episcopal School of Ministry, Pittsburgh, PA


Believing the Bible in the Global South, Convocation Address, Graduate Theological Union, Berkeley, CA, September 2006.


The New Faces of Christianity, Erasmus Lecture, New York City, October 2006. I also spoke on this topic at the Carnegie Institute on Ethics and International Affairs.


Global Schism: Is the Anglican Communion Rift the First Stage in a Wider Christian Split? Pew Forum on Religion and Public Life, Key West, FL, May 2007.


In June 2007, I spoke at the Conference on Islam and Muslims in the World Today, organized by the British government, and held in Lancaster House, London


God’s Continent: Europe’s Religious Crisis, Cardinal Joseph Bernardin Lecture, University of South Carolina, Columbia, SC, October 2007


Religion and Science, Christian Worldview Conference, Princeton, NJ, November 2007


Now That Faith Has Come, Plenary address, Evangelical Theological Society, San Diego, November 2007


In December 2007, I delivered the paper ‘Black Gangs’: The Perils of Counter-Subversion, to the colloque on Mimicry in Civil Wars: The Strategic Use of Identity Signals, held at the College de France, Paris.


Islam and the Future of Europe (with George Weigel), Ethics and Public Policy Center, Washington DC, February 2008


Islamic Europe or Euro-Islam? Workshop on Institutionalization and Representation of Religion, Berlin, Germany, June 2008


The Transformation of Gender and Family in Emerging Asian Christianity, Summit on Chinese Spirituality and Society, Beijing, China, October 2008


Religious America and Secular Holland: Future Trends, Conference on Four Centuries of Dutch-American Relations, Vrije Universiteit, Amsterdam, Netherlands, October 2009.


The Futures of Christianity, Svenska Kyrkans Forskardagar, Teologiska Högskolan Stockholm, Sweden, December 2009


Have the Culture Wars Gone Global? The Faith Angle: Conference on Religion, Politics and Public Life, South Beach, FL, March 2010.


Future Trends in Religion, Panelist, with George Gallup, jr, and Roger Finke, University Park, PA, April 2010.


The World's Religious Map in 2050, Penn State Forum, University Park, PA, April 2010.


Religious Authority and the Challenges of Modernity, The Archbishop of Canterbury’s Building Bridges Seminar, Georgetown University, May 2010.


The Bible in a Changing Christian World, keynote lecture at United Bible Societies World Assembly, Seoul, Republic of Korea, September 2010.


The Globalization of Christianity, Keynote lecture at conference on Our Common Future, Essen, Germany, November 2010.


The Lost History of Christianity, Radboud University, Nijmegen, Netherlands, May 2011


Religion in Modern Europe, Károli Gáspár University of the Hungarian Reformed Church, Budapest, Hungary, May 2011


 Christianity, Islam and Europe’s Religious Crisis, Vrije Universiteit, Amsterdam, Netherlands, May 2011.


Eight Lessons from the History of Terrorism, Conference on The Future of Terrorism II, University Park, PA October 2011.


I participated in a panel on Confronting Islamophobia at the annual conference of the American Academy of Religion, held in San Francisco, November 2011. I also chaired a panel at this conference on Global Charismatic and Pentecostal Healing.


Evangelicals, Pentecostals, and Charismatics, International Conference on New Religious Movements as a Challenge for the Catholic Church, organized by the German Bishops' Conference, Rome, Italy, April 2013.


Christianity and World History, Wilberforce Weekend (Colson Center), Arlington VA, April 2013.


Out of the Past: Child Abuse in Religious Settings, STAND conference for North American Mission Leaders, Dallas TX, September 2013.


From Wittenberg to Lagos: The Sixteenth Century Reformation and Modern-Day Global Christianity, at Protestantism? Reflections in Advance of the 500th Anniversary of the Protestant Reformation, 1517-2017, Gordon College, Wenham, Mass., November 2013.


Faiths at War, Custodire l’umanità: verso le periferie esistenziali, Assisi, Italy, November 2013


Reshaping Faith: How The First World War Transformed Christianity, Judaism and Islam, Frederick C. Wood Lectures, Cornell University, Ithaca NY and Cornell Club, New York City, April 2014.


Culture and Faith, Napa Institute, Napa CA, July 2014


The Middle East: Violence and Religion, St. Vincent's College, Latrobe PA, February 2015.


The Great and Holy War, Berry College, Rome GA, February 2015.


Houston’s Nigerian Churches, (Read on my behalf), Texas State Historical Association, Corpus Christi, TX, March 2015


The Image of God in Global Faith, Wheaton Theology Conference, Wheaton IL, April 2015. This was also Wheaton College’s McManis Lecture.


Demographics and Global Faith, Christian Scholars Conference, Abilene TX, June 2015. My work was also the subject of two panels at this event.


Religion, Violence and Scripture, Chautauqua, NY, July 2015.


The Demographic Dimension of Global Christianity, Commemorative Conference on the Basel Mission 1815-2015, Basel, Switzerland, September 2015.


Godless Europe? End of Religion symposium, National Press Club, Washington DC, November 2015.


Christianity, Islam and Holy Wars, at conference on Mere Anglicanism: The Cross and the Crescent, Charleston SC, January 2016


The Last Holy War? Teach-in on the First World War, University of Oklahoma, Norman OK, March 2016


It's Bigger on the Inside: Decline, Growth and Transformation in Contemporary Religion, Society of Christian Philosophers, Pacific Division, San Diego CA, March 2016


Faculty Mentor, Sixth Enoch Graduate Seminar, Austin, TX, May 2016


Conversation on Global Trends: New Demographics and their Implications, Pew Foundation, Washington DC, July 2016


Childhood’s End, Inklings Society, Oxford England, July 2016


Fertility and Faith, Association of Statisticians of American Religious Bodies, Waco, TX, October 2016


The Western Frontier: Euro-Islam and the Remaking of Global Faith, Missiology Lectures, Fuller Seminary, Pasadena CA, November 2016.


Chair and Discussant, Panel on The Anglican Communion and the First World War, North American Conference on British Studies, Washington DC, November 2016.


Secular Europe? Texas Baptists Annual Meeting, Waco TX, November 2016.


Invited Participant, Foresight Conference on Global Futures, Singapore, July 2017


Pineapple and Herring: Protestant and Catholic Missionary Strategies in the Early Modern World, Conference on Celebrating 500 Years Of The Reformation, Hong Kong Baptist University, Hong Kong, September 2017.


Reformations: Past, Present And Future, Florida International University, Miami, FL, October 2017


The Eastern Churches, Conference on Coming Home from Genocide, Anglosphere Society/Hudson Institute, New York City, December 2017


The Church in an Era of Change, Meeting for the Friendship of Peoples, held at Rimini, Italy, August 2018, 


1918 and 1968: Crisis, Catastrophe and the Remaking of Religions, King University, Bristol TN, September 2018


The Great War and the Holy War, Fahrhochschule für Interkulturelle Theologie, Hermannsburg, Germany, November 2018


The Ghosts of Churches Past, Landregan lecture, University of Dallas, Dallas, TX, February 2019


Crucible of Faith, Colorado Christian University, Denver CO, October 2019


Keynote speaker on “Faith, Religion and World War One,” Lilly Endowment workshop, National WWI Museum and Memorial, Kansas City, MO, January 2020


Climate, Catastrophe and Faith, Flagler College, St Augustine, FL, January 2020


Africa and the Global Church, City to City Africa, October 2020


Faith and Fertility, The Media Project, October 2020


Christianity Today: Prospects and Trends, First Presbyterian Church, Augusta, GA, February 2021



I have on several occasions served as a speaker and panelist for workshops on religion and violence convened by the RAND Corporation in Arlington, VA.



In addition to these lectures and seminars, I have also spoken frequently in different venues in the US and overseas, chiefly on aspects of global Christianity, and the expansion of Christianity in the global South. These events include:


Carnegie Institute on Ethics and International Affairs, New York City, April 2002

Westminster Theological Seminary, Philadelphia, PA, September 2002

John Randolph Club, Rockford, IL, October 2002

Baylor University, Waco, TX, November 2002

St. Vincent's College, Latrobe, PA, November 2002

Anglican Congress, Atlanta, GA, December 2002

Anglican Mission in America, convention, Pawley’s Island, SC, January 2003

National Cathedral, Washington

DC, February 2003

St. Anne’s Church, Annapolis, MD, February 2003

Siena College, Albany, NY, February 2003

Shawnee State University, Portsmouth, OH, March 2003

St. Thomas University, St Paul, MN, March 2003

Northwestern University, Evanston, IL, April 2003.

Gonzaga University, Spokane, WA, April 2003.

Evangelical Christian Publishers Association, Orlando, FL, July 2003

Juniata College, PA, September 2003

St. Vincent's College, Latrobe, PA, September 2003

University of Oklahoma, Norman, OK, September 2003

Catholic University of America, Washington DC, October 2003

Messiah College, Grantham, PA, October 2003

Mother Church of Christian Science, Boston, MA, October 2003

University of Hawaii at Manoa, Honolulu, November 2003

Overseas Missionary Study Center, New Haven, CT, December 2003

University of San Francisco, January 2004

Cathedral Church of the Advent (Episcopal), Birmingham, Alabama,

February 2004

St. Mary’s University, San Antonio, TX, February 2004

National Association of Evangelicals, Colorado Springs, CO, March 2004

Hanover College, Hanover, IN, March 2004

Seton Hall University, South Orange, NJ, March 2004

Boston College, March 2004

Canisius College, Buffalo, NY, April 2004

SUNY Plattsburgh, Plattsburgh, NY, April 2004

Chicago Center for Global Ministries, April 2004

Pallium Lecture, Archdiocese of Milwaukee, May 2004

Capitol Hill Campus (Mercatus Center), Washington DC, May 2004

Virginia Baptist Missionary Board, Richmond, VA, September 2004

Dickinson College, Carlisle, PA, September 2004

John Carroll University, Cleveland, OH, September 2004

Wesleyan University, Middletown, CT, September 2004

Heritage Foundation, Washington, DC, October 2004

Missions Conference, San Antonio, TX, October 2004

Association of Adventist Forums, Hueston Woods, OH, October 2004

Grace Presbytery, Dallas, TX, November 2004

St. Louis University, January 2005

La Sierra University, Riverside, CA, February 2005

Dominican University, Chicago, February 2005

North Central University, Minneapolis, March 2005

Lebanon Valley College, Annville, PA, March 2005

Gordon College, Massachusetts, April 2005

Columbia Union College, Takoma Park, MD, April 2005

St Michael’s College, Burlington, VT (Sutherland lecture), April 2005

Wheaton College, IL, April 2005

Northern Seminary (Chicago) April 2005

Association of Vineyard Churches, Columbus, OH, May 2005

Council on Foreign Relations, Washington DC, May 2005

The Gathering, San Antonio, TX, October 2005

Radboud University, Nijmegen, Netherlands, October 2005

Calvin College (January Series), January 2006

Walla Walla College, Walla Walla, WA, February 2006

Mississippi State University, Starkville, MS, February 2006

Houghton College, Houghton, NY, March 2006

Missions Congress, Freising, Germany, May 2006

University of Copenhagen, Denmark, May 2006

University of Aarhus, Denmark, May 2006

Waynesburg College, Waynesburg, PA, September 2006

Brigham Young University, Provo, Utah, October 2006

St. Vincent's College, Latrobe, PA, November 2006

Princeton University, Princeton, NJ, November 2006

Boston College (Candlemas lecture), February 2007

Abilene Christian University, Abilene, TX, March 2007

Church of the Incarnation (Episcopal), Dallas, TX, March 2007

Union College, Barbourville, KY, March 2007

Asbury Seminary, Wilmore, KY, March 2007

Institute on Religion and Democracy, Rosslyn, VA, March 2007

Nebraska Wesleyan University, Lincoln, Neb., April 2007

Wycliffe Bible Translators, Orlando, FL, June 2007

Rochester College, Rochester, Mich., June 2007

Ablaze Conference – Lutheran Church Missouri Synod, Houston TX, July 2007

National Conference on Innovation, Columbus, Ohio, September 2007

Villanova University, Villanova, PA, October 2007

Fox Leadership Program, University of Pennsylvania, Philadelphia PA, November 2007

Loyola University, Baltimore MD, January 2008

Eastern University, Philadelphia PA, February 2008

House of Hope Presbyterian Church, St Paul, MN, February 2008

Beeson Divinity School, Birmingham AL, March 2008

Centre for Theological Inquiry, Princeton NJ, April 2008

Niagara University, Lewiston NY, April 2008

Mormon History Association (Tanner Lecture), Sacramento, CA, May 2008

Covenant College Leadership Forum, Reynolds Plantation, GA, September 2008

King’s College, Wilkes-Barre, PA, October 2008

King College, Bristol, TN, October 2008

Indiana Wesleyan University, November 2008

Aurora University, Aurora, IL, January 2009

Grove City College, PA, February 2009

Bethel University, St. Paul, MN, February 2009

Air Command and Staff College (USAF), Montgomery, AL, March 2009

Pepperdine University, Malibu, CA, March 2009

St Andrew’s Presbyterian College, Laurinburg, NC, April 2009

Youth Conference, Assyrian Catholic Church of the East, San Jose CA, July 2009

Duke Divinity School, Durham, NC, October 2009

Campbell University, North Carolina, February 2010

Veritas Forum, Texas A&M University, February 2010

Lehigh University, Bethlehem PA, March 2010

International Forum of Bible Agencies (FOBAI), Fort Worth, TX, April 2010

Boardman Lecture, University of Pennsylvania, Philadelphia PA, April 2010

International Lutheran Council - World Seminaries Conference, Fort Wayne, IN,

June 2010

Palm Beach Atlantic University, West Palm Beach, FL, October 2010

Grosse Pointe Memorial Church, Michigan, December 2010

Myers Park United Methodist Church, Charlotte NC, February 2011

Union/PSCE Presbyterian Seminary, Charlotte NC, February 2011

Virginia Commonwealth University, Richmond, VA, March 2011

Hope For Europe II, Budapest, Hungary, May 2011

McMaster Divinity School, Hamilton, Ontario, June 2011

Maryknoll Seminary Alumni, Maryknoll, NY, September 2011

Derry Presbyterian Church, Hershey PA, October 2011

First Presbyterian Church, Philadelphia PA, October 2011

Canisius College, Buffalo, NY, November 2011

Bishop Elliott Society, San Antonio TX, November 2011

Synergize 3, Orlando FL, January 2012

St. Charles Borromeo Seminary, Wynnewood, PA, January 2012

Oklahoma Baptist University, Shawnee, OK, February 2012

Butler University, Indianapolis, IN, February 2012

Malone University, Canton OH, March 2012

SUNY Geneseo, Geneseo NY, April 2012

Evangelical Christian Publishers Association, Leadership Summit,

Hoffman Estates, IL, May 2012

Global Summit, Church of the Foursquare Gospel, Phoenix AZ, June 2012

Episcopal Church of St Michael and All Angels, Dallas, TX, October 2012

University of Tennessee Chattanooga, Chattanooga TN, February 2013

University of South Carolina Upstate, Spartanburg, SC, March 2013

Wisconsin Institute for Public Policy and Service, Wausau WI, September 2013

Union University, Jackson TN, October 2013

Mount Aloysius College, Cresson PA, October 2013

Luther Seminary, St. Paul, MN, October 2013

Pastors’ Retreat, Camp Buckner, Burnet TX, October 2013

Winter Pastors’ School, Stetson University, DeLand FL, January 2014

World Catholicism Week, DePaul University, Chicago, April 2014

Wycliffe College, Toronto, Canada, May 2014

Concordia University Irvine, Irvine CA, June 2014

Valparaiso University, Valparaiso IN, September 2014

Golden Gate Baptist Theological Seminary, Mill Valley CA, November 2014

Presidential Leadership Intensive Conference, Association of Theological Schools, San Antonio, TX, January 2015

Austin College, Sherman TX, February 2015.

Norwegian School of Theology, Det teologiske Menighetsfakultet, Oslo, Norway, March 2015

Misjonshøgskolen, School of Mission and Theology, Stavanger, Norway, March 2015.

Hardin-Simmons University, Abilene TX, October 2015

Hartwick College, Oneonta, NY, January 2016

Southern Methodist University, Dallas TX, April 2016

Presbyterian Foundation, Portland OR, June 2016

Georgetown College, Georgetown KY, January 2017

McMurry University, Abilene TX, March 2017

Jacksonville, FL. St. John’s Episcopal Cathedral, and Riverside Presbyterian Church, October 2017

Christ Church Austin, TX, July 2019 (delivered by Skype)

St. Vincent's College, Latrobe, PA, October 2019