(quote from RealReality.org/Real_Faith_and_Reason_Vol_2_-_Scientia.pdf)
Assumed Premises versus True Premises
Let’s get back to the basics of logic. Rational thought must have true premises. We must prove the premises. We need a reason to believe the premises. The reason must be rational. It must be absolute. We need to know the premises are absolute and true.
To illustrate, suppose I insist I know the Bible is God’s word based on sound reasoning. Then I say my premise (proof) is I assume it, and I take my assumption as an axiom. I presuppose my axiom.
My assumed axiom: “I assume the Bible is God’s word.”
So the ungodly thinker insists the Bible isn’t God’s word and also says she bases her claim on sound reasoning. And the ungodly thinker takes the following assumption as an axiom.
The ungodly thinker’s assumed axiom: “I assume the Bible isn’t God’s word.”
Why is my assumption better than the ungodly thinker’s assumption if I can’t even prove it to myself? Since assumptions are made up, they aren’t part of reality. How can made-up stuff prove something else is real?
I insist on the following:
It makes sense to interpret scientific observations based on the Bible.
It makes sense to interpret historical artifacts based on the Bible.
My interpretation of scientific observations proves the Bible’s authority.
My interpretation of historical artifacts proves the Bible’s authority.
I can trace my premises back to my original assumption of the Bible’s authenticity.
The ungodly thinker insists on the following:
It makes sense to interpret scientific observations based on the writings of ungodly people.
It makes sense to interpret historical artifacts based on the writings of ungodly people.
Her interpretation of scientific observations disproves the Bible’s authority.
Her interpretation of historical artifacts disproves the Bible’s authority.
The ungodly thinker can trace her premises back to her original assumption of the Bible’s unreliability.
The premise is the proof. And yet, we must prove the premise to ourselves. How do we prove a premise? Of course, we certainly can’t use another unproven premise. What good would another unproven premise do? And we can’t just declare made-up stuff to be an axiom since applying the label “axiom” has no power to make the made-up stuff true. But if we can’t prove a premise is true, the premise is unknown. And we can’t use the unknown to prove anything. Without a true premise, we can’t know anything at all. However, we’ve already identified a way we can know reality with certainty. This way is divine revelation through Jesus Christ.
The ungodly thinker can claim you aren’t experiencing what you’re experiencing. The ungodly thinker can refuse to look at the evidence. (The evidence is that anyone who sincerely continues to seek Christ will find Christ. When they find Christ, they will know.) If you say you assume, you have just claimed the ungodly thinkers made-up stuff is competing with your made-up stuff. You had a solid reason to believe, but you gave it up. By assuming the Bible is God’s word, you secretly accept the atheist presupposition that God doesn’t reveal anything to anyone.