That is why I and others consider morality to be subjective but still very important. When we think of what is moral, one of the first things we should do is look to our own sense of morality, our own emotions, and our own needs and wants in life. That is subjective.
I also don’t see this as a problem for Christians, theology, or theism in general. If religious belief and practice helps you be a moral person, then by all means be a theist. If you believe that God helps you understand subjective morality better and treat others more justly because of it, then great. I have no argument against that whatsoever.
I think one of the underlying lines of argument is that if morality is subjective then morality isn’t important. I think that is absolutely wrong. Our wants and needs as humans are the most important things in the world to us, and they are subjective. There also seems to be the argument that God must exist because morality is objective, but how many people truly came to God because of that argument? People claim to be in a relationship with God, so would that relationship suddenly disappear if the moral argument disappeared? I don’t see why it would.
Just to sum it up, when I, as an atheist, say that morality is subjective it isn’t meant to be an attack on theism, nor is it an attack on morality itself. It isn’t an argument for anarchy, nihilism, or amorality. It is simply an acknowledgement of where our morality comes from, and I think that knowledge can help all of society, theist and atheist alike.