an·tith·e·sisnoun \an-ˈti-thə-səs\ 1. the exact opposite of something or someone. 2. the state of two things that are directly opposite to each other
"Whoever is not with me is against me, and whoever does not gather with me scatters."
I got the book Pushing the Antithesis through American Vision's online store. It's based on Greg Bahnsen's teaching and written and compiled by Gary DeMar. In my opinion, and from what I've read of reviews online, it would have to be one of the best books there is on Presuppositional Apologetics.
It's well laid out and makes some of the more complex issues in apologetics understandable. In a nutshell, to push the antithesis means to show that biblical faith and unbelief stand in direct contrast. It is either God or absurdity - there is no neutral middle ground. It's not God or some other worldview that is almost as good as Christianity - it's the biblical God or ones worldview reduces to absurdity. If people don't start with God in their thinking then they absurdly cannot know anything - they cannot account for anything according to their worldview. "The fear of the Lord is the beginning of knowledge, but fools despise wisdom and instruction." (Proverbs 1:7).
Bahnsen and DeMar make it clear that a big part of our job in apologetics is to "push the antithesis" and show that if a person denies God that they cannot make sense of anything and end up with a foolish system of beliefs. As it says in Proverbs 26:4-5 "Do not answer a fool according to his folly, or you yourself will be just like him. Answer a fool according to his folly, or he will be wise in his own eyes."
In particular I found chapter 11 on 'The Problem of Universals' really helpful in better grasping the problem unbelievers have of reasoning from limited experience to universal concepts and laws. These things make sense in the biblical worldview but cannot be accounted for without God. We take for granted universal concepts and laws in order to function in the world and in order to have rational conversations - but without God there is no reason for these universals.
Another thing I found helpful was thinking about the question "Which worldview makes sense of the world we live in?" When we consider this we find that the biblical worldview alone can account for and make intelligible concepts like human experience, laws of logic, rationality, and human dignity.
The book also discusses many of the absurd results of rejecting God. Some of the more extreme and dangerous absurdities are things like widow burning, genocide, child sacrifice etc - without God there is no way to account for why these things are wrong. Understanding this has made it even clearer to me why as Christians we need to speak out against the sin of abortion which is a modern day holocaust and something that many non-Christians don't see it for what it really is - the murder of innocent children that God loves.
In summary, if you only read one book on apologetics I'd say that this is the one to read.
Further Reading / Research: