Maybe we should start with an analogy: the Pledge of Allegiance. “I pledge allegiance to the flag of the United States of America, and to the Republic for which it stands . . .” It goes on to describe the benefits of that Republic: a unified populace (“indivisible”) which provides “liberty and justice for all.”
The Pledge is about the Republic. It’s about a particular form of government, a particular kind of polity, a relationship between the people and their government set forth in the Constitution. The flag is just a symbol; it could be made of a different design, of different colors, or not exist at all, and the Republic would remain. It’s not about the flag, but what the flag stands for.
So too for “God”. Both atheists and religious believers tend not to see it, but the divisions in the country (and the world) over “God” are far less about Him, and far more about what He is said to stand for. God is invoked as a symbol for a comprehensive world-view and way of life. He may be said to require a certain relationship between authority (religious or secular) and the people, a certain kind of social and family order (the nature of marriage and the relationship of the people in a marriage to each other), a certain kind of morality (sexual and ethical), certain kinds of actions (circumcision, genital mutilation, refusal to eat shellfish) and a certain tribalism among adherents (no intermarriage, or even contact with people who are not believers in the same religious creed). And many other aspects of life.
In God the symbol, if He is absolutely unitary or part of a trinity; if there is only one or many; if he revealed himself to the Jews, the Arabs or the Chinese – or even if He does not, in fact, exist at all – the point is not the symbol, but what it stands for.
Since the beginning of time, God (in some form) has been advanced as the giver of laws. The comprehensive Code of Hammurabi invoked a god as the source of law – but the law itself was secular, and whether or not it was given by a god, or what the nature of the god was, was immaterial. The purpose of the god was to add symbolic force to a set of rules that the authorities of the day deemed useful to society.
The Ten Commandments, which many Christians claim is the source of laws, does something similar. The first three or four (depending on the version you choose) of the Commandments establish God as the giver and enforcer of the laws, and the remainder are rules that serve the purposes of the society regardless of the nature of God, or whether he exists. God (or a god, or gods) are the symbols which validate the rules they are said to establish.
Take away the symbol (God or the flag) and the order that it stands for tends to remain, because it serves the purposes of those who advance and revere the symbol. That point is often forgotten by atheists who argue against the existence of God, and against strictures alleged to have been put in place by Him. It’s not about God; those strictures are there because believers want them there. It may be important to believers to defend the symbol, just as it may be important to patriots to defend the flag. But neither symbol is essential to the underlying order it represents.
Of more importance is that underlying order. Is there a problem with the way the government relates to its people? Changing or eliminating the flag does not fix that; a Constitutional amendment may. Is there a problem with the rules God is said to have established? Changing the rules is far more important than changing or eliminating God.
There is, of course, one major difference between the flag and God. The flag is a passive symbol; it is not said to cause rules or relationships to come into being, but God is claimed as a source for rules. That fact gives some sense to the atheist notion that belief in God has to be undermined to effect social change. Even so, Christian activists are quick to point out alleged injuries to society caused by a violation of God's rules - which shows that they believe there is a secular justification for the rules apart from