Mortal Coil, VOY 4
Neelix is pronounced dead for 18 hours but Seven of Nine uses Borg tech to bring him back. The fact that he did not experience the Talaxian afterlife shakes Neelix and creates an existential crisis. Chakotay (since he’s all, like, spiritual) tries to help, but even he can’t do anything. Neelix defeats suicide, but just barely.
For Voyager, a great episode. And for Trek in general – it is interesting to touch upon religious issues among Starfleeters. The sponsors keep the Terrans from doing this too much. Only Talaxians, Bajorans and Space Native Americans can get into it – not regular folk.