Many Christians celebrate the birth of Christ on December 25th, even though Jesus was almost certainly not born on December 25th. Since pagan groups in the ancient world had celebrations that coincided with the Christian celebration of the birth of Christ, is Christmas pagan? In this video, Marie Wood discusses the issue.
For more on this topic, watch these videos by Inspiring Philosophy:
In this lecture, Greg Koukl (of Stand to Reason) explains the "Columbo Tactic"—a strategy for navigating discussions with non-Christians by asking key questions.