Here we have the introductory statement. It is sort of like a cannon shot across the bow where Paul asserts that men "stuff the truth." Mankind does it. It is evident that God exists and that there is a Creator. And not only that there is a Creator, but this God also provides for His creation. He cares for it. He is concerned about it. He loves it. But men still stuff that and they suppress the truth in unrighteousness.
In this case the truth was the evidence manifested at creation that there is a Creator God. The lie, in this context, is the idol. They exchanged the fact of a Creator for something that they could see and say, "This is our god."
In Paul's explanation, truth comes very close to being personified, that is, given life. And it is almost as if truth, being a living thing, is held down, strangled, and throttled until its very life is almost gone. That is why he says here (I substituted the word "stuffed") the truth is "stuffed" and if stuffing of the truth is allowed to continue unchecked, then it is inevitably going to lead to idolatry.
Now catch that. That is very important to pick from what Paul is saying. The idolatry will be a direct consequence of ignoring the evidence of the truth of the existence of the Creator God, because if that is ignored or stuffed or suppressed, then what is the natural consequence? The natural consequence of that is man is left on his own to devise his own means of worshipping a god.
Is man going to come up with the truth about the Creator God on his own? It is impossible. Absolutely impossible. Because whatever representation he comes up with is going to automatically be a lie because he does not know what God looks like since he is stuffing the existence of a Creator God. He does not really know how that Creator God thinks. He does not know the Creator God's purpose. He does not know the whys, the wherefores, or the hows of that Creator. So whatever he comes up with is going to be idolatry.
What is he saying? He is saying people know. They know what is right. They know that there is a God. He has shown it to them. If they claim they do not know, they are lying; they are simply remaining willfully ignorant of that, and He says they have no excuse.
So they do not want to worship God because He places restrictions on them. He places responsibilities on them. They ignore His law. They ignore all the ways that He has shown that He is there and He is enforcing His way, and so God says they are without excuse. They have done it to themselves.
In Romans 1:22-25, Paul describes the unrighteous as those who change the glory of the incorruptible God into an image made like corruptible man. Paul calls them fools. He says they exchange the truth of God for the lie. Trying to make God like a man is a lie. And foolish.
