12. What is the Christian's Presupposition?
As noted earlier, whatever Christians do, think or say needs to be grounded in the truth of the Bible. We shall love God with all our heart, soul, and mind (Matthew 22:37). The first commandment is to have no other gods before Him (Deuteronomy 5:7). The Hebrew literally say “you shall have no other gods before my face” or in my presence; it doesn’t suggest we can have God first and whatever else second and third.
Peter puts the authority of Scripture higher even than any of his own empirical experiences as we have seen before and which is worth repeating (2 Peter 1:16-19). Note his use of the phrase more fully confirmed: “And we have the prophetic word more fully confirmed” than his own eyewitness account, more sure than anything to him. For Peter, the word of the prophecy (the Bible) is his ultimate authority. It is his presupposition. It is that by which he interprets everything else, including his personal experience.
For a Christian, the Bible is his ultimate authority, and because it is such, you cannot appeal to something else to prove it.
In presuppositional apologetics we present Christianity based on the word of God as the only worldview by which human knowledge is even possible, as opposed to evidential apologetics, which argues for a high probability of the truth of the Christian faith based on evidence discussed by unbelievers and believers in a neutral way using unaided human reason. When we look through the scripture, we will never find the Bible treating God’s word as probably true but as completely certain. Here are just a few examples of the many in the Bible:
As Christians we can’t appeal to a humanistic measure to try to figure out if what the Bible says is true or not. Trying to do so is always an unsuccessful endeavor. The Christian author C.S. Lewis writes: “A creature revolting against a creator is revolting against the source of his own powers - including even his power to revolt. ... It is like the scent of a flower trying to destroy the flower.” (C.S. Lewis, A Mind Awake, p104) As Christians we really shouldn’t be joining unbelievers in their revolt against God by assuming another ultimate authority. We have to appeal to God as ultimate authority. Wait a minute though – isn’t this circular reasoning? Not at all. Think about it. If an unbeliever says: “Reason is my ultimate authority”, you should normally ask: “How do you prove that?” Now he would answer by either saying: “Reason proves it”, in which case it will be circular; or he would say: “X proves it”, where “X” could be anything (science, human agreement, common knowledge, and so on), in which case “reason” is no longer his ultimate authority but “X”. When we are talking about “ultimate authority”, in the nature of the case it must be self-verifying and self-authenticating. You cannot appeal to anything outside your ultimate authority to prove it.