Augustine argued that reason and faith complemented one another. Faith, then, is not credulity. Faith is dependent on the rationality endued to us by our creator. There is no virtue in believing that which is absurd.
Logic is an intellectual governor, protecting us from proceeding into falsehood. Aristotle defined logic as the necessary instrument for intelligible discourse. Evidentialists like Normal Geisler or John Warwick Montgomery believe that via sense perception we can come to a high degree of certainty of Christianity.
Sproul does not embrace evidentialism. Empirical evidence is important to the Christian faith, but our sense perceptions can deceive us. We look into the water from a canoe and see the oar bent in the water – the oar in fact is not bent, it is merely the refraction of light that makes it seem to be. Sproul, like Augustine, would prefer to start from something certain—self-consciousness. Descartes was on to something when he famously quipped “I think, therefore I am.” To even doubt one’s existence requires thinking, and thinking requires existence.
Yet thinking, like existence, does not reside in physical matter. Our minds are not physical matter. Though they are connected to our brains in this life, upon our death, we have continuity of personal existence via our minds.
And going beyond Descartes, with the awareness of certainty comes an awareness of our finitude. And from an awareness of our finitude, comes (inescapably) an awareness of God. How? Existence implies one of three possibilities:
1. I am eternal.
2. I am self-created.
3. I am created by someone who is eternal.
Most atheists today advocate self-creation in some form. But for something to be self-created it has to be there to do the creating. It has to be there before it is there. This concept violates the law of non-contradiction.
If ever there was a time that there was nothing, what there would be now…is nothing. If something exists, then something must have always existed. God is ontologically and logically necessary. Our existence is not necessary; the world could exist without us. God is necessary; nothing could exist without Him. And God is logically necessary. Our finite, derived being logically implies his infinite, self-existent being.
God immediately (without means) reveals himself to us in our minds: Our self-consciousness argues inescapably for our existence, and our finitude, which implies the existence of God (a self-existent, infinite being). We can know, with certainty, that God exists.