Which Religions Besides Christianity Incorporate the Notion of Salvation?

[Ahimsa]

In other words, is it the case that because of Jesus, all will be resurrected and have eternal life, but the nature of that eternal life may be heaven or hell, depending on the person?

True. That’s orthodox Christian belief.

And what of those who died before Jesus was born?

They will be resurrected along with those who died after Jesus was born.