Easy. The Son has to die, meaning every human individual must die because ONLY that way the evolution of DNA can proceed. DNA can "go to heaven", meaning beyond the death of the individual, for future generations to live, and to repeat the same cycle.

DNA has a mechanism for aging, meaning we really die because of it, not in spite of it. The Aging has been built in (= has evolved as a trait) because it allows the species to evolve when older generations leave room for newer ones.