Doing Apologetics: "From Below" or "From Above"?

Karl Barth spoke of doing theology "from below," in distinction from doing it "from above." If someone starts out looking at this natural world and tries to inductively conclude something about God, (or the supernatural realm "above"), he cannot do it, Barth would claim. Only if someone starts "from above" in presupposing God (or the supernatural realm), and tries to explain the natural world from that presupposition (for him the Bible as a "witness"), can it be done. My professor Dr. James D. Strauss argued likewise, although he is no Barthian. He would argue "we either start with God or we'll never get to God." So a big question is in trying to justify our starting point. Do we start "from above," or "from below"?

As a Thomist, Norman Geisler’s arguments start “from below.” His apologetic includes 12 steps: 1) Truth about reality is knowable; 2) Opposites cannot both be true; 3) The theistic God exists; 4) Miracles are possible; 5) Miracles performed in connection with a truth claim are acts of God to confirm the truth of God through a messenger of God; 6) The New Testament documents are reliable; 7) As witnessed in the New Testament, Jesus claimed to be God; 8) Jesus’ claim to divinity was proven by an unique convergence of miracles; 9) Therefore, Jesus was God in human flesh; 10) Whatever Jesus (who is God) affirmed as true, is true; 11) Jesus affirmed that the Bible is the Word of God; 12) Therefore, it is true that the Bible is the Word of God and whatever is opposed to any biblical truth is false.”[1]

The thing about Geisler's twelve apologetical steps is that his whole case will fall to the ground if any one step if shown faulty. I'm not even so sure about his first step!

However, isn't it obvious that if you must presuppose God, then you may begin with a false presupposition to begin with? If humans have such a strong tendency to defend what they were raised to believe, especially when it comes to religious beliefs, then they will probably be able to defend whatever they first presuppose. And if that's the case, their arguments probably beg the question.

[1] From Baker’s Encyclopedia of Christian Apologetics (Grand Rapids: Baker Books, 1999), “Apologetics, Argument of"