The USA, even with all of its problems, injustices, evil, and greed, is still considered to be a nation that, as a whole, believes in God. Things would be a whole lot worse if there was no belief in God at all. Besides, all genuine Christians have the Holy Spirit, the third person of the Trinity, indwelling them, who is referred to in the Bible, as a restraing influence.
A restraint against unrighteousness and evil gives evidence that there is a God, does it not? What other explanation might YOU have?
Men and women have free will to live apart from God, or to not believe in God at all. People have a free will to make choices and decisions. In cultures with no belief in God, this free will reveals the nature of man's character at its worst. In cultures with belief in God, the nature of mankind is tempered with the restraining influence of the new spiritual nature given to those who truly seek and receive God's love, grace, and mercy, not by merely attending church, but by entering into a personal relationship with their creator.
People often ask the question, "If there is a God, why is there so much evil in the world?" Let me turn that question around and ask, "Why do so many people choose to use their free will to do evil and make poor choices?" Does that not in itself show that there is something wrong with human nature without a belief in God? Even if you want to blame human behavior on the environment or a person's upbringing, the issue is still one of exhibiting free will.
Consider cultures that have no godly influence at all. I have read stories, and have heard people who have visited them, talk about their experience. There are unthinkable things happening, like cannibalism, or other barbaric deeds, with absolutely no regard for human life.
If you choose to not believe in God, or have little regard for Him, go live in a culture like I just mentioned, and see the result for yourself. You will see the fallen and sinful nature of humanity, at its worst. You would probably end up booking the first flight out of the country, and come back to ANY culture that has a Godly restraining influence.
It is because of a belief in God that we don't see nearly as much evil in the world as we would otherwise.
Now back to the USA. As we are drifing further and further away from spiritual truth and belief in God, there is also an increase in evil and violence. That ought to tell you something. As a whole, our culture is not living by the Ten Commandments, given by God to Moses thousands of years ago. If we were, you do not have to be told how different our culture would be.
This article has been written primarily to atheists or people who have little regard for God. I hope it has begun to show a connection between cultural behavior and belief in God.