SMT is probably my favourite JRPG series. SMT3 (Nocturne or Lucifer's Call) and Persona 5 are two of the best games ever made, for sure. There are definitely religious themes in a lot of SMT games but they're generally superficial. To be honest, the whole point of the religious aspect imho is to justify monster designs based off of world religions and mythology, and that's one of the reasons the games are so compelling
Still haven't finished SMT4 or started Apocalypse, because of that stupid alignment system. I won't let myself play the sequel until I get the neutral ending