The foundational scripture for the Answering Difficult Questions Workshop is in 1 Peter 3:15 "But in your hearts revere Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect."
The key word in this verse is "answer" (Greek: apologia). Apologia means "to give an account (legal plea) of oneself", from which we have the word "apologetics", which is simply the defence of our faith.
There are essentially three approaches in Christian apologetics:
1) Classical apologetics (Thomas Aquinas): The foundation of this approach is Reason (rationalism) and the approach is philosophical. It presupposes that a pre-believer who follows the logical arguments for God's existence will come to faith in God. Example: Aquinas' "five proofs" (the "cause & effect" argument): where is an effect (motion, matter, being, degree or design), there must be a first cause (God).
2) Evidential apologetics (Josh McDowell): The foundation of this approach is Evidence (empiricism) and the approach is empirical. It presupposes that a pre-believer who is given the scientific "facts" will come to faith in God. Example: the evidence of fossils, intelligence design in biology, creation science, etc.
3) Presuppositional apologetics (Francis Shaeffer): The foundation of this approach is Worldviews (pluralism) and the approach is confronting presuppositions. Example: Darwinists are committed to an atheistic presupposition and will reject any argument or fact that suggests divine origin of the universe as a matter of principle. So no argument or fact, no matter how logical or scientific will be accepted by those who are committed to a worldview contrary to the Christian worldview.
The approach adopted in the Answering Difficult Questions Workshop is presuppositional apologetics. The focus of presuppositional apologetics is NOT in giving the "right" ANSWERS (rejected as matter of principle by those committed to a non-Christian worldview) but in asking the right QUESTIONS about the questioner's worldview - with the aim to show its inconsistencies and contradictions to real-life experiences.
However, not all non-Christian guests on Alpha are committed to a naturalistic worldview. Many are simply unconscious that they have adopted a naturalistic worldview as they have been secularised by Western science and technology, social & business practices, and through the mass media and movies. The goal of presuppositional apologetics is to uncover the unbiblical presuppositions and to affirm the Christian worldview as the only one that can explain meaningfully the whole of human existence regarding our identity (who am I?), origin (where did I come from?), purpose (why am I here?) and destiny (where am I going?).