I had a teacher in school who believed in predestination. Basically, whether you go to heaven or hell is pre-ordained before your even born and there's nothing you can do to change it. I told him that sounded to me like I should be a Satanist because if I'm predestined for heaven I've worshipped Satan all my life for nothing and I get to chill in heaven. If I'm predestined to go to hell I've spent so much time worshipping Satan it probably won't be too bad. I'm personally not really religious myself but I really was dumbfounded at the whole predestination thing.

You see, there are these things called eigenvalues. They dimentionalize the vector space. We can contruct a personality vector space and assign a set of orthogonal personality vectors. (Sees that this is elif). Erm, think of a "which Harry Potter character are you" quiz. We can add and subtract weighted , erm, Harry Potter characters, to get to you. You are half Harry plus two Rons minus 1.5 Malfos.

Now those numbers might change over time. That is you at that moment. If you, erm, took a DeLorean back to 1955, but still had those same numbers, you would still be you. If you wiped your memory but still had those numbers, you would still be you. Stands to reason if you went back in time and got your memory wiped, you would still be you. What if someone in the past (or future) had the exact same numbers? That would be you, even though no time travel occurred.

Now (erm, how do I explain vector projection to a five year old), ummm, if your numbers are close, you are mostly you? Now Jesus, ahh, scored a particular score on the sigh Harry Potter quiz. Remeber how I said your numbers change? Well, if your numbers are close enough, you could say that he is you, or Jesus is living Through you. And as long as more people in the future get numbers close to both yours and Jesus's, you could say you are living on, or having eternal life. And in order to change those number to Jesus's, you have to be good.

What? Oh, yes I got Hermonie. How did you know?

Answer according to anyone christian: (note- not me) You don't. You have have to "Be sorry" and "ask forgiveness". You can still be an enormous piece of sh*t if you say you're sorry that you were bad.

Welp you don't want to hear it but the best explanation is religion is a system to scam commoners of their devotion and money. If things start not making sense then you should stop believing in Santa Claus