I was brought up in a religious family. I even brought a family I was friends with into a church when I was around 11 years old Pretty sure they're no longer in the church either. I drew a picture of how I imagined god looked like when I was around 12. I've been an atheist ever since I was around 16 but still doubting for years after that though it was weakening before that A what if? I never told my parents I've been to churches all over the countries and most were pretty similar with some exceptions. Some I felt were cold, or cruel (I did a play with a pentecostal church when I was about 14... Horrible thought process from my perspective even then).
I understand people still believing in some form of deity but not going to churches or visa versa, I don't do either as an adult. I feel wrong in churches and find far more interesting and testable answers for spiritual experiences something our own human bodies can create. My what if doubt disappeared with universal math as the god gap (and any god/deity not even specifics) I could see it never became more likely. I don't see it possible for me to 'get my faith back' so to speak but my faith in ideas never disappeared. I like the study of religion and the ancient, I believe in the absoluteness of how what a schizophrenic will feel/see as clearly as we see each other and I think Gods exist in our minds but only that, I think people are curious and will act on that for better or worse.
Anyway back to the title. Can you explain to me reasons why people return to theism?