One that comes to mind is “Religion for Atheists”. It is a great book that highlights the non-spiritual functions of religion in society. The idea is by identifying what function you got out of religion in the past, you may find ways to replace it without getting involved in the collective delusion of pretending to know the unknowable.

If you’re stepping away from the god of Abraham, you could always read Nietzsche’s “The Antichrist” but i dont really recommend most people read Nietzsche without some solid footing in philosophy and some helpful context, since he can lead people to some straight up Nazi shit which he elsewhere explicitly warned against. Context important with him. But it’s a scathing criticism of the role of dogma in society.

If you feel a need for a spiritual drink without relapsing on god, I recommend exploring the Dao De Jing. It’s another one that benefits from context, rereading, and meditation, but it can explain the world quite nicely without need of an invested anthropomorphic god.

Finally, you might want to pick up some existentialist literature if you feel like life has no meaning and you’re lost. Sartre or Frankl come to mind.