It's been said that as early Christians went to preach about Christ and his virgin birth, his tests, miracles, death, resurrection, and divine pedigree, the people they were preaching to would essentially say, "Oh yeah, we have that too!"
It's almost a cliche to point out that Mary and Jesus resemble Isis and Horus, that Gautama faced his tests as well, that Heracles is the son of Zeus and a mortal woman named Alcmene.
But when this is pointed out, suddenly an intelligent design argument appears to explain it.
"Satan Did It!" The devil himself is attributed the ability to inspire people for millenia beforehand to tell stories about a demigod born of a virgin. This also envisions Satan as having the foresight to do so.
The alternative explanation, of course, is that a lot of mythology was developed around a man called Jesus after he died, assuming he lived at all.* In this case, there is no need for Satanic inspiration, no need to give Satan a new superpower of foresight, and really no need for Satan at all.
One of these explanations demands a rewrite of science to account for spirit creatures and what abilities are available to them and reeks of a conspiracy through the ages. The other explains how the myths developed without any such leap.
I know what I'm putting my money on.
But what gets me is this argument from ignorance about an intelligent designer. In this case, the intelligent designer is Satan the Devil weaving myths instead of Yahweh causing things to become. If you say this, you are asserting that the existence of mythology similar to that of Christ is evidence of an intelligent, malevolent designer, just as the existence of very complex life is evidence of an intelligent designer.
In response to intelligent design, complex life is not irreducibly complex. It can be broken down and shown to have evolved. Similarly, the mythology about Christ can be broken down and shown to have evolved by numerous writers and influences over the course of decades and centuries. Indeed, the 4 narrative gospels were written in later decades by unknown authors AFTER Paul had reached out to the Gentiles, and there was some logic to how they attributed each one to Matthew, Mark, Luke, and John. And within 4 centuries, Jesus was God.
An additional argument to all of this is that all mythology and religion disseminated from a single origin (namely Babylon). This is to support the Satanic inspiration argument. It argues that two similar, complex ideas must have had the same source. It is a long discredited idea that, first of all, disregards how far flung, populous, and fairly advanced humankind was 5000 years ago. It disregards the major differences in myths from around the world. It disregards psychology. It disregards that you and I can have the same or similar idea, even around the same time without having the idea disseminated to us -- the classic example being Leibniz and Newton independently creating Calculus.
* As I wrote in another thread, I personally do believe there was a historical Jesus. However, I don't believe all that has been attributed to him, or in the integrity of the Bible.