Romans 1:24-25 - "Therefore God also gave them up to uncleanness, in the lusts of their hearts, to dishonor their bodies among themselves who exchanged the Truth of God for the lie, and worshipped and served the creature rather than the Creator..."
The greek term used here for "gave them up" is a judicial term used for handing over a prisoner to his sentence. When men consistently abandon God, He will abandon them. He does this sometimes directly by specific acts of divine judgement and punishment (flood, Sodom, etc.). And He sometimes does this indirectly by removing His restraint and allowing their sin to run its inevitable course. Here, Paul is speaking of God indirectly giving men up to uncleanness of sexual immorality. The Greek word used for "uncleanness" is a general term often used when speaking of decaying matter. God abandons those spoken of here and allows their sin of sexual immorality to run its course which begins in the heart and moves outward to shame the body decaying the soul.
Men who deny the existence of the Almighty God of the Bible worship and serve the creature rather than the Creator. Most men (without admitting it) worship and serve themselves because of this popularity within our culture to establish that truth is whatever one personally believes to be true. John MacArthur speaks of this in his book, The Truth War....
"Postmodernism in general is marked by a tendency to dismiss the possibility of any sure and settled knowledge of the truth...... Nothing is certain, and the thoughtful person will never speak with too much conviction about anything. Strong convictions about any point of truth are judged supremely arrogant and hopelessly naive. Everyone is entitled to his own truth."
This can be clearly examined through general conversation. You hear people all the time making comments such as.... "Well, I don't think God is exactly like that". I would then follow by asking what this particular person bases their beliefs about God on. You might hear something such as.... "Well, its just what I believe". So their beliefs about God are based on their own personal thoughts and opinions. They have become their own personal god and established their own false truth that fits their pleasure. I'll end with this.....
When asked by someone which of the religions of the world gives to its followers the greatest happiness, CS Lewis responded.... "While it lasts the religion of worshipping oneself is best..... If you want a religion to make you feel really comfortable, I certainly do not recommend Christianity."