You don’t need religion for ethics or worldview. How about: we all appear here on this rock, none of us know why, we’re all in it together, we all struggle, none of us know if we’re alone in this universe or what the universe really is. This unifies us all and puts us on an even playing field. We should be compassionate to one another as we all come from the same circumstance. We can create a concept of god to explain it, or accept that we don’t know for sure and maybe never will. God is a choice, but not the only one.
This kind of argument, while moral on a surface level, belies a misunderstanding of human nature. In Jungian terms, it assumes that the shadow self either does not exist or has been fully integrated without confrontation.
Once one has enough power and experience to achieve one’s goals despite opposition, and to use others instrumentally, the moral calculus can become difficult. We do not all start from the same circumstances: I am writing this on a phone produced by slave labour.
As Lenin might have said: “compassion for whom?”
You say “God is a choice”. Solipsism is a choice.
This exhibits the borrowing GP mentions: your ‘should’ does not necessarily follow from the stated priors. Why is compassion morally mandated by the priors and not competition, for example?