There is a massive tradition, spanning thousands of years, of people trying to wrestle with morality and the good life with or without a God involved. We broadly call it Ethics in Philosophy, and you can spend an entire lifetime exploring and glimpsing what is at the core of this "being a good human" with or without a God involved.

On "good comes from religion"... you can start with the western classics (or eastern classics, but I do not know them) https://plato.stanford.edu/entries/plato-ethics/ https://plato.stanford.edu/entries/aristotle-ethics/

Then maybe take a course or two on Ethics https://ocw.mit.edu/courses/linguistics-and-philosophy/24-23...

Then explore from there.

You can spend a few weekends or a lifetime on this if you'd like, and either way it will be worth the time.