Is it possible not to die?

Answer 1

According to some religions, it's theoretically possible under extraordinary circumstances.

For example, Elijah and Enoch are stated not to have died, but to have been "taken" by God.

Also, it's implied in the New Testament in several places that all Christians who are still alive at the time of the Second Coming of Christ will not have to die.

Aside from that, though: No. Advances in medical technology could theoretically make it possible to extend a person's lifespan, but a non-zero cosmological constant implies that even that has a limit (though it's extremely far in the future) and that you'll die in the Big Rip if not before.