We've got some pictures here of a grandfather of one of the people here. So basically this is when he was a baby, then this is when he was a young man, then this is when he was a middle-aged man. And then what do you call this? Old man already, right? See, there are very great differences, especially if, for example, you go from the baby to this one. Then here's a picture of just before his departure [death] there. It's such a radical difference there.

You know, here's a person, the baby body is there, and then you see the old man body and you flash, where is that baby body? The baby body's here and then it's left behind, and then there's a young man body, a completely different body, all different molecular parts, all different atoms, all different material, yet the person's still the same. I'm still me, right? Now I've got a baby body, I've left that behind, and now I've got a young man body. Then I leave that behind, and then I've got an old man body. Do you understand this?

Siddhaswarupananda, founder of the Science of Identity Foundation

For the soul there is never birth nor death. Nor, having once been, does he ever cease to be. He is unborn, eternal, ever-existing, undying and primeval. He is not slain when the body is slain.
BHAGAVAD GITA 2.20