Less often discussed is the problem that, actually, all the evidence points to the fact that God, if he exists, is the greatest relativist of them all.
Let's say, for example, that you are a Christian. In the Book of Leviticus, there are all sorts of bizarre sounding rules, laid down by God, which Christians no longer feel themselves obliged to follow. These include the death penalty for homosexuals and children who do not respect their parents, bans on eating hares and calamari, prohibitions on men trimming their beards and approval for slavery. Most Christians believe, however, that the New Testament supersedes the old and that these rules no longer apply. What this adds up to is the belief that what was wrong for the ancient Israelites is not wrong for modern Christians, on God's command. That seems to me like a clear combination of relativism and the belief that God's will underpins ethics.
In many ways this should not be surprising, since many have argued that the trouble with divine command theory - the idea that what is right or wrong is what God commands - is that it leaves open the possibility that God could command what is currently wrong to be right and vice-versa. Christian texts seem to provide evidence that this is precisely what Christians should believe.
There are many people who also, rather hopefully in my view, hold to the view that God makes himself manifest to people in different ways, and so it's not the case that only one of the world's religions is right and the rest are wrong, but that all are right in their own ways. But again, since they make different moral demands of people, if that is true, God must be a relativist, for he requires different things from Jews, Hinduism, Sikhs, Muslims. Christians and members of any other religion.
The strange thing is that I have often found religious people very sanguine about the idea that, as circumstances change, God might require different things of different people in different places at different times. But these same people are horrified by the idea of relativism. There seems to me to be a very clear contradiction between these two sets of attitudes.
Honk if you love Jesus!!