As atheists, we are accustomed to being asked, "Where do your morals come from?"
The oft-spoken assumption is that the world has reason to fear and hate atheists because there is nothing to restrain the atheist from committing horrible atrocities. Which is why the question itself identifies the person asking it as a bigot - seeking to promote an unfounded hatred and fear of others.
The common atheist response is to present a theory of morality. Morality is an evolved disposition, or morality is that which produces the greatest happiness for the greatest number, or morality is a social contract we all implicitly adopt.
Or, morality resides in the fact that desires are malleable and people generally have reason to promote those desires that tend to fulfill other desires and inhibit those desires that tend to thwart other desires.
However, another form of response is available to those who claim they get their morality from God.
"Where did God get his morality?"
The correct answer to this question, of course, is that God gets his morality from his inventors.
"What you are doing, sir, is taking your own personal likes and dislikes and assigning them to God, then telling the world that God gives you permission - even commands you - to impose your preferences on others. Or you are the blind follower of somebody else who assigned his preferences to God, and then deceived you into promoting his interests by telling you that you are really working for an imaginary super-being that he invented."
This is the fact of the matter. This is also what is wrong with most religious morality - that religion provides a way for individuals to justify in their own mind imposing their own interests on others by assigning those interests to an imaginary super-being called God, then convincing oneself or others that, "No, you are not serving my interests. You are serving God's. The fact that serving God's interests coincides so closely with serving my interests is simply testimony to the depths of my spirituality."
The elm tree in my front yard exists. The evolutionist and the creationist might disagree over the history that brought elm trees into existence to start with.
Here's an absurd form of argument.
"Elm trees come from God. You do not believe in God. Therefore, obviously, you cannot believe in elm trees. As an atheist, you cannot account for elm trees so you are at risk of walking around the world bumping into elm trees and crashing into elm trees because you cannot account for their existence."
We do not hear that argument much. In part, we do not hear it because of the absurdity of it. We may disagree on how elm trees came about, but that does not imply that we must disagree on whether the elm tree in my front yard actually exists.
The same is true of morality.
One attitude to take is that the atheist and the theist disagree on how morality comes about. However, this does not imply a disagreement over the actual existence of morality. The person who wants to accuse the atheist of having no morality needs to provide more than evidence that the atheist does not believe in God. He has to provide evidence that not believing in God is necessarily associated with moral blindness. If morality is real, this is as absurd as saying that not believing in God makes it impossible to see elm trees.
So, why do we see this argument with respect to moral principles and not with respect to elm trees?
Because people who use the argument with respect to moral principles have a drive to promote hatred and fear others. The motivation for the argument is not that the argument makes sense - because it makes little sense for morality as it does for elm trees. The motivation for the argument is to tell the members of the congregation (or the school assembly or the legislative chambers), "You should hate and fear them because nothing restrains them from committing the most atrocious of evils."
Of course, "hate and fear them" immediately translates into, "love and trust me." It is a way for the speaker to promote himself (or his church) by putting down others. Thus, bigotry becomes hate-mongering; the act of selling hate to others for the purpose of personal gain.
An atheist and a theist can have a perfectly legitimate discussion over where elm trees some from. The theist can hold that there can be no elm trees without God. In other words, a conversation about where morality comes from is a perfectly legitimate subject for two good people to engage in.
However, the view, whether explicit or implicit, that atheists are to be hated and feared because they do not believe in God and, thus, are liable to all sorts of evils is not a thesis that a good person can advance. It is as absurd as the thesis that the atheist cannot see a elm tree. Somebody who is blind to that absurdity is either a bigot who adopts such an attitude out of a sense of hate, or a hate-monger seeking personal gain by selling hatred to others, or both.
Interestingly, the thesis, "God gets his morality from those who invent him (and God is being continually re-invented)," does not support the type of hate-mongering bigotry that is used against atheist. It does not support the conclusion that all theists are to be hated and feared. Instead, it supports the thesis that a moral theist will invent a moral God, while an immoral theist will invent an angry, petty, jealous, violent, destructive, and/or bigoted God.
Here's a slogan that might be of some use.
Since God gets his morality from those who invent (or re-invent) him . . .
"You can tell a lot about a person by looking at the qualities of the God he invents."