To be honest, in Scripture, celebrating His birth isn’t something that G-d seemed to find to be of importance; however, since Yeshua’s birth is part of the Redemptive plan, I believe His birth exists within the Feasts, specifically Sukkot (Feast of Tabernacles). I believe, among the other theoroies, it brings in the most Scriptural evidence on the Hebraic calendar, prophetically and that the Romans wouldn’t have done a census in the Winter, either.
Our family has never made it a point to celebrating it and it’s not something that is “absent”. We mention it, reading all the Scriptures referencing it; emphasizing the prophetic nature of the conception, since Yeshua could not have the ‘sin of Adam”, His circumcision, His presentation at the Temple (Luke 2) to fullfil Torah, but the only thing I do is set out a small wooden nativity scene (with no wise men, since they weren’t there then, only shepherds). Other Messianic Believers do other things; it’s not a Command so there is flexibility and you can incorporate it into the week, mainly the first day for the Birth along with G-d’s Commands for an assembly and no work; for example, some Believers sing the “Christmas” songs, like “Little Town of Bethlehem”, etc. on that first day of Sukkot.
There are so many wonderful ways to observe The Feast of Tabernacles, some in Scripture, some man-made, and we’ve just come off the heels of the Fall Feasts. It doesn’t take a backseat in our mind, but it’s not the only thing going on that week. Here’s a good run-down of the different theories, though I don’t put a lot of faith in the traditions of the early church fathers mentioned at the bottom for a variety of reasons-http://www.hebrew4christians.net/Articles/Christmas/christmas.html
Hope that makes sense! Basically, you can make His birth as big or as small a deal as you like; I just think it shouldn’t replace what’s required for the Feast of Tabernacles established by G-d Himself, but man-made traditions can (and are by many) definitely be incorporated into it with joy; as long as the “tradition” doesn’t “make null and void the Word of G-d”(Matt. 15:6).
As for his death and Resurrection, I’ll make that a separate post.
Rachel