Dr. Walter Martin used to discuss it on the Bible Answer Man program. I'm not sure of the details so you may be right about that. I'm not well read on the subject matter, in fact, I've never actually researched the material. Just relating something I've heard for whatever it might be worth.
I'm likewise, not sure where you are getting your information but at the top of a google search I found this:
Roman Mithraism was a secretive mystery religion. It had secret initiation rites with no public cult. Mithras was a cthonic deity, with subterranean Mithraea temples, but a Banquet with the Sun motief is very common within them, so had some relation to the mythos. It seems as if Hellenistic astrology was an important aspect and perhaps entailed ascension through the heavenly spheres as devotees passed the various grades of the religion. For this reason, 19th century antiquarians connected it with the increasingly popular cult of Sol Invictus of late Roman times, but there is no Roman source making this connection. Mithras thus has no connection with Sol Invictus or any public cult, beyond conjecture.
The real story is that Sol Invictus was set up by the Emperor to compete with Christmas, which was celebrated for at least 100 years prior around Dec 25. St Nicholas' tradition came from when, as bishop, one of his flock had 3 daughters, and no money, and whose only recourse was to sell them into sex slavery. St. Nicholas provided, in small money pouches, a dowry for each one of them, preventing that sale.
The only time I actually looked into this was when I was debating doubtingmerel on the Carrier thesis. Apparently the initiating rites had a series of questions at eight levels, each level representing the eight planets. We wouldn't have hardly any of those questions because like you say, it had an exclusive membership, you had to be initiated. The point here being there is no indication that it had anything to do with the sun or stars, just the planets. Still it was a very popular mystery religion, supposedly most Roman soldiers were initiates. Mithra was kind of a warrior figure, fighting some kind of a bull he dragged to a cave and slew, so that might have been part of the appeal.
Pentecost came exactly 50 days after Passover, all Jews were required to attend in Jerusalem as a matter of Law. The reason I consider Easter to be the only legitimate Christian holiday is because Christ was betrayed on Passover, the Lord's Supper being modeled after the Passover meal and initiated during Passover. It is not a Holy Convocation like the ancient Hebrews had under the Law, there is no religious compulsion to observe it as a requirement for fulfilling some religious duty. However it is inextricably linked to vital events in redemptive history, the Crucifixion and Exodus respectively.
The holiday was created before the competing Sol Invictus was created. In fact, Sol Invictus was celebrated to compete with Christmas, which was already celebrated by Christians for at least 100 years on or about Dec 25.
That's very true, when Jesus told the Apostles to wait for the coming of the Holy Spirit, apparently what they were waiting for was Pentecost. When you think about it it was the perfect time to send the Jews of the Dispersion home with the message of the gospel. A number of important traditions lay claim to being founded at Pentecost. When Paul writes the church at Rome he was probably addressing the church there that was founded at Pentecost. So I can see what you mean, I'm just not real comfortable with having some high holy day in New Testament Christianity, it might tend to be thought of as some legalistic religious duty.
That's more or less what I'm getting from all of this. In that sense I really don't have a problem with Christmas I'm just a little stand offish about this somehow being identified with pagan traditions. No self respecting Christian then or now would knowingly do any such thing. The only thing the two traditions should really have in common is a date on the calendar.
I know. I'm just playing the trumpet. The practices people use to celebrate Christmas have pagan origins-candles and trees and reindeer and such. But Christmas is about celebrating our Lord's birth. Not presents and drinking egg nog. I ask my Confirmation students each year something like this:
Not all, but many. We have more martyrs in the 20th century than all the others combined.
I think the COGIC churches, the big Pentecostal denomination, have something reminiscent of the ancient Hebrew, Holy Convocation, they even call it that. These things are all perfectly fine by me, I remember my Aunt trying to explain the Rosary to me. Apparently it is representative of the various events of the New Testament. Passover, it should be noted was reminiscent of the Exodus, Tabernacles of the wilderness wanderings etc. As people of faith we identify with long and time tested traditions that remind us of redemptive history past, present and even casting some light on the future. My feeling is that if you can partake of the Lord's Supper without remembering how much our sin cost him you might as well be eating potato chips. In all these things the forms are not as important as the substance found in Christ. If it helps you draw closer to God and remember the landmarks of redemption it can be a profoundly important practice. But just going through the motions yields little if we are just dutifully following some prescribed liturgy. It just depends.
Feel free to expound from your source material because I'm not seeing much of a research challenge here.
