I don't think it's so cut and dry. I grew up protestant Methodist and it wasn't an unforgivable sin, it views it as a natural death by disease (depression). But other protestant churches demonized it, I don't know if all but definitely Baptist, Nazarene, & Lutheran. Catholics do too, but not a protestant church. I don't know about other religions' thoughts on it so can't say for certain. But there is for sure one that doesn't (Methodist). So I think it largely just depends. No clue what Judaism says on it.