OK let's start with crucifixion. This is plausible ... lots of men were crucified, and lots of men were called the Hebrew/Aramaic equivalent of Jesus. However, unless a crucified man called Jesus can be shown to be the same person who had a virgin birth, performed miracles, and/or, most importantly, rose from the dead, then it really tells us nothing special at all.
Resurrection. This is
the central plank of Christian faith. No resurrection means no Christianity, period. However, it's impossible, both biologically and logically - "death" means the end of life, after all - so it could only happen if an interventionist god fiddled with his own laws of nature (or logic) to perform a miracle. Either the impossible happened, or the core belief of Christianity is false - I can see no other alternative. In any case, suppose someone was put up on a cross, believed to be dead, laid in a slab in a cave, and emerged alive a day and a half later (not three days ... he was cut down before sunset [Shabbat] on Friday and was seen walking around early Sunday morning), would you believe (a) he hadn't actually been dead, and he recovered in the cave, or (b) he was dead, but God intervened to bring him back to us? I appeal to common sense and Occam's Razor on this one.
Nativity. Well, as I've already shown, the two accounts in Matthew and Luke disagree in almost every detail, so if one is right the other has to be wrong. Personally, I think it's most likely both versions were made up.
Let's gloss over the contradictions for a moment and assume there was just one Nativity account. How did it come to be part of the gospel(s)? Consider two possibilities ...
Scenario 1: The amazing events of his birth were well known and a matter of record at the time of his recruiting of disciples and entry into Jerusalem. Odd that there is no mention in Roman records of either a census or a slaughter, but never mind. Presumably at least one disciple would have said something like "Hey, aren't you the guy who was born in a stable with a star over it, who got expensive gifts from those Eastern chaps, and escaped to Egypt while all of our older brothers were being exterminated?" ... Were these tales well known to the gospel writers, and they only had to add the crucifixion and the events around them to complete the story?
Scenario 2: Imagine the interview ...
Matt/Luke: "Mary, we are very sorry for your loss, but we are writing up your son's life for posterity. Is there anything you can tell us about his early life to fill in the background?"
Mary: "Well, now that you ask, there were some things that I never thought to mention before. There was this really bright star directly above the stable, and it didn't move across the sky with the other stars. Then of course there were these rich blokes with their expensive gifts. Why did we keep the carpentry business when we had all that gold? Better ask Joseph. Never so much as bought me a necklace. And of course there was that angel scaring the hell out of the shepherds. Then we had to leg it to Egypt for a while because all of the first-born babies were being killed. You never heard about that? Well, yes, it was rather well suppressed. Odd that people didn't talk about losing so many children, though. Oh, and when he was a bit older he went to the Temple and taught the rabbis the right way to interpret the scripture - I'm surprised they didn't sling 'im out on 'is ear. Is that the sort of thing you were looking for?"
Do either of these scenarios seem at all plausible? If not, perhaps you could tell us how you think the tales from the two ends of his life ended up in the gospels.
[As an aside: If the magi could travel from countries in the East in less time than it takes Mary and Joseph to check out from the stable, and the family could travel to Egypt in less time than it takes Herod's soldiers to track them down, how come Moses and his people took 40 years to get from Egypt to Canaan?]
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