He didn't rise from the grave if you read the Bible, because he was not dead. He was not left on the cross long enough to die, and according to Jewish custom he was taken down on the Friday and placed in a mortuary
I don't think he existed at all.
I have heard the "He wasn't quite dead." theory. It assumes the Romans kind of sucked at the Crucifixion thing.
What you think means nothing, science has shown that a man called Jesus son of Joseph was alive in that period
It shows that even under armed occupation the Jewish laws were still upheld and no one was allowed to hang on the cross over the Sabbath. I assume that like all other wannabee atheists you only look at the parts that suit your tiny little mind