The source of your source on Horus is pretty dubious. I was pretty heavily into Ancient Egypt and while I can agree the Horus-myth has a lot in common with the Christ myth I think some of those comparisons are a little off:
- Horus born of a virgin. <> Jesus born of a virgin.
Technically true, because when Isis remade Osiris, she couldn’t find his penis. In most versions of the myth, Isis still manages to give Osiris a blow-job somehow. In some versions she even managed to have sex with him! Plus Isis and Osiris had been married before Osiris was dismembered and it can be pretty safely assumed that they had engaged in coitus. So, his birth wasn’t the result of a normal sexual union, but there is no way to know whether Isis was a virgin because . . .
More importantly, the Ancient Egyptian language didn’t have a word for ‘virgin’. At least insofar as we can tell (most Egyptologist do assume the Egyptians were aware of the concept). Now, the cult of Isis that spread from Egypt to much of the rest of the Mediterranean and was popular with certain elements in the Empire (think Hinduism/Buddhism in the '60s) and it is possible that the notion of virginity was introduced there. But since it is already known that Christianity is a mystery cult, it resembling a mystery cult shouldn’t surprise us too much.
- The foster father of Horus was Seb or Seph. <> Jesus was fostered by Joseph.
Seb (Geb) is Osiris’s father and the Earth god. As in literally the Earth. We are standing on Geb right now. I’ve never heard of him interacting with Horus in a foster-fatherly role. Again, the mystery cult may have changed this.
- The birth of Horus announced by angels. <> The birth of Jesus announced by angels.
Not in any of the versions of the myth I am familiar with. Maybe the mystery cult threw it in, but I’m trying to think of an Egyptian equivalent of Angels. Plenty of minor deities, though I am unaware of any of them heralding Horus’s birth.
- Horus had 12 followers. <> Jesus had 12 disciples.
I know of his four sons involved with the canopic jars. Who are the other 8?
- Horus was killed by crucifixion. <> Jesus was crucified.
I’ve never heard of Horus being crucified. Any examples, ideally pre-dating the establishment of Christianity in Egypt?
Both Christ and Horus are monomyths so it makes sense that their stories would have many similarities. Though the ones cited here don’t appear to be the similarities in question. I mean, really. During a Pharaoh’s life, they are Horus and when they die they become Osiris. So you have a really clear case of a son and a father being contained within the same entity. That would be a good angle to take with respect to Christianity and Horus. And it is possible that Christianity was partially inspired by that story.
As for the personage of Jesus, you have to remember that history wasn’t a rigid discipline back in the day, so you have to view it through that lens. For example, the Talmud talks about a Rabbi who sounds very much like Jesus, except it would date him to 100AD and he was executed by hanging. My guess is that the Jesus of the Bible is a combination of several different people (which also explains his in congruent actions) that were fused into one individual in a mystery cult that became very popular. Probably initially by co-opting John the Baptist’s cult.
Since I am coming at it from a non-literalist view, I don’t really have a problem pointing at any, or all, the figures that went into Jesus and say, “Yeah, that’s Jesus”. I imagine one of them was probably a charismatic healer and member of John the Baptist’s cult, or at least involved with it in some manner. And he probably ran afoul of the Roman authorities. Though I can see where it would be problematic for someone coming at it from the standpoint of belief.
Edit: And I can’t really see what this has to do with ‘science’. Some astronomy, sure. But only as it relates to the religious question.