The apostle Paul sees the wrath of God which is coming upon the unsaved. He must preach.
Today many believe in evolution, God did not make anything. They scrabble about to find another solution, another explanation, however far-fetched. I am not responsible for my conduct. There is this theory of an unconscious self within me, and things are buzzing around in my unconscious department – all to my training, or my genes, or something else – and these are the things that make me behave as I behave. It is not my fault. By false religion, by sheer brute atheism, the truth is suppressed and conscience can be quiet, so I can do what I like. And the settled indignation of God is against all those things, and Paul sees it, and he knows that there is a price to pay, and the gospel therefore has to be preached. There's a constant campaign in the world to suppress, to pull down, to hold down the truth of God. You go to school and you learn religious knowledge and what do they mostly teach you? Attacks on the Bible, foolish attacks, ideas that undermine the Bible. This is not inspired by God; this is not revelation. This is the work of men and it contradicts itself, and all sorts of spurious examples are brought forward, none of which hold water. Right from the Garden of Eden where Satan said to Eve, ‘Hath God said?’, the casting of doubt is constantly there. Some do it through rationalism – evolution and so on – others do it in a religious way – the Church of Rome. The Council of Trent puts a curse upon anybody who would teach that the salvation which comes from God is altogether free, and Christ totally, entirely earned it for us.