The two predominant philosophies of argumentation within Christian apologetics are evidentialism and presuppositionalism. William Lane Craig, JP Moreland, and RC Sproul are evidentialists. Greg Bahnsen and James White are presuppositionalists.

Evidentialism holds that religious beliefs are only rational if they are based on evidence. They employ much history, philosophy, and science in their argumentation and seek to find   common ground with their opponent before working toward their position.

Presuppositionalism is often associated with Cornelius Van Til (and his students Greg Bahnsen and John Frame) because he so persuasively argued that most human beliefs depend on unprovable basic assumptions and are shaped by faith or the lack of it. Presuppositionalists are not interested in finding common ground, acknowledge their presupposition that the Bible is true and therefore use it forcefully and freely. When charged with circular reasoning, the presuppositionalist shows that his opponent also has presuppositions regarding his source for truth, be it reason, the Qur’an or whatever.

Here is an example of how to spot an evidentialist.

In a debate between William Lane Craig and Shabir Ally on the resurrection of Christ, Ally argues that the spear thrust to the side of Jesus was only a prick and quotes Raymond Brown. Muslims love quoting Catholic scholars who undermine Scripture, which is just the same as saying Catholic scholars.

A presuppositionalist would answer thus. “That can’t be true. John 19:34 says that the spear so penetrated the side of Jesus that blood and water came out. He was unquestionably dead.”

This is how William Lane Craig, an evidentialist responded (at 1:18:30):

Assuring the death of crucified victims by a spear thrust into the heart to make sure he is dead is attested in classical sources. For example, Quintilian attests this. So this is not just in the Gospels.

It wasn’t until the Q & A time that a non-PhD from the audience even brought up John 19:34.