Most people believe in God--some kind of god--but it's a different thing altogether to believe God! And our text makes it clear that believing God simply means believing what He says, "that it shall be even as it was told me." Paul spoke these words at the height of a terrible storm at sea, when it appeared certain that "all hope that we should be saved was then taken away" (v. 20). But God had spoken otherwise, and Paul believed God rather than adopting the fears of those around him. Abraham, "the father of all them that believe" (Romans 4:11), had set the example. "He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; And being fully persuaded that, what he had promised, he was able also to perform" (Romans 4:20-21).
God does not speak to us audibly today as He did to Abraham and Paul, but He does speak far more comprehensively to us through His written Word, and we have even less excuse for unbelief than they might have had. It is a terrible offense against our Creator to question His Word. This, indeed, was the very sin of pride that led to Satan's fall and then to the fall of Adam and Eve. "All scripture is given by inspiration of God |literally, 'is God-breathed'|" (2 Timothy 3:16) and thus should be fully believed and explicitly obeyed, for "he that believeth not God hath made him a liar" (1 John 5:10).
But what about those Scriptures that modern scientists claim to be wrong? "Shall their unbelief make the faith of God without effect? God forbid: yea, let God be true, but every man a liar" (Romans 3:3-4). "For the word of the Lord is right; and all his works are done in truth" (Psalm 33:4). HMM