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
: 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 .
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
, 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.
Pew Forum on Religion and Public Life, Key West, FL, May 2007.
In June 2007, I spoke at the , 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
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
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,
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,
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