James M. Harrison summarized and explained the purpose of Christian Presuppositional Apologetics when he wrote the following concerning its role in the discipline of Christian apologetics:
{{cquote|That which I will attempt to describe in this article is known as presuppositionalism. It is an apologetic method which has had the most impact in Reformed circles, and is most closely associated with [[Cornelius Van Til|Cornelius Van Till]], [[John Frame]], and the late [[Greg Bahnsen]].
I should begin by pointing out that the Presuppositional Apologetic does not discount the use of evidences in apologetic reasoning. It does not use evidences in the traditional manner, however. By the traditional manner, I mean using evidences as an appeal to the authority of the unbeliever's autonomous reasoning. The problem is, of course, that the unbeliever cannot reason autonomously. Without [[God]], there would be no possibility of reason. And so the reality of the matter is that every time the unbeliever attempts to reason, he is borrowing from the [[Christianity|Christian]] worldview. That is, he is being inconsistent with his stated presuppositions. And that is the crucial point. Ultimately the intellectual conflict between believers and unbelievers is a matter of antithetical worldviews. The essence of the Presuppositional Apologetic is the attempt to show that the unbeliever's worldview drives him to subjectivity, irrationalism, and moral anarchy. And so the Presuppositional Apologetic calls for the Christian and non-Christian to set side by side their two worldviews and do an internal examination of them both in order to determine whether or not they are consistent even within their own framework. Since God does exist, and since Christianity is true, then any worldview which denies these truths are false and can be demonstrated to be so.<ref>http://www.gospeloutreach.net/papol.html</ref>}}