A nice collection of presuppositional apologetics has been posted here, on American Vision. Check it out!
But what is presuppositional apologetics, anyways? It is the stance that…
“…only the Christian worldview provides the necessary preconditions for the intelligibility of human experience. That is, only the Christian view of God, creation, providence, revelation, and human nature can make sense of the world in which we live. So, for example, only the Christian worldview can make sense out of morality since it alone provides the necessary presuppositions for making ethical evaluations, namely, an absolute and personal Law Giver who reveals His moral will to mankind.
It does not make sense, however, for the atheist/materialist to denounce any action as wrong since, according to his worldview, all that exists is matter in motion. And matter in motion is inherently non-moral. That is, since the world according to the materialist is totally explicable in terms of physical processes, and since physical processes are categorically non-moral, moral considerations have no place in his worldview. Thus for the materialist to say that stealing is morally wrong makes as much sense as saying that the secretion of insulin from the pancreas is morally wrong.
[This is not to say, however, that atheists never act morally. Atheists feed their children, give money to charity and often make good neighbors. But atheists cannot give a justification for their actions. In the words of Cornelius Van Til, they are living on “borrowed capital” from the Christian worldview. Thus they profess one thing, but their actions belie this profession].
— Michael Butler, from Monergism.com
[Note: I broke up the above quote into three pieces, for readability.]