Perhaps the better question to ask is how the 25th got into the big discussion...being the Winter Solstice. Somewhere along the last thirty years of Emperor Augustus (63 BC to 14 AD), this was a festive period created where gifts were exchanged, caged birds were given as gifts, candles were lit, and the general dress code was relaxed.
I think the Catholic Church attached itself to the festival and just linked up the birthday to fit Solstice, and continue the fest period.
Mostly because in ancient people believed they died on same day they were conceived.. We know Christ died in late March/April so he was conceived in December so that is why December 25 is celebrated for Christmas. Paganism has nothing to do with why Christmas is celebrated when it is.
The only way to keep up with God's days is to follow the Jewish calendar. I'm sure Satan chuckles every year as he watches Christians celebrate pagan days thinking they are honoring Christ. Halloween is getting as big as Christmas. Santa and reindeer have nothing to do with Christ and bunnies and chocolate eggs have nothing to do with Christ.
Doing a word search in The Bible for "watch" will reveal several verses pertaining to the Last Days. If we read those verses, God stresses we are to be WATCHING! Watching for what? The Feast Days in Leviticus. Feast means Moed which refers to a dress rehearsal. A holy convocation refers to an arranged time. So God is saying to be watching for Him to do something on these days that you rehearse what was given in Leviticus. Jesus was truly born on Trumpets, but I don't think we can know the exact year with the info we have. Most of it is speculation from 2-4 BC or so. We do know He was born on Tabernacles, so why are we celebrating Dec 25? We know He died on Passover, was buried on Unleavened Bread, and rose on First Fruits, but observe Easter. We are frightened to celebrate Pentecost, afraid we might start speaking in tongues. So now that Trumpets is 10 days away, we refuse to Watch, afraid God will rapture His church and all will come true. I've even had people joke that I hope He doesn't come this year because I have a cruise coming up in November.
There are people "watching" but they are very few. If the Rev 12 sign is in the sky as we speak, and this is a Jubilee year, and the UN will declare "International Peace and Safety" on Trumpets this year, then maybe, just maybe, some should look up as our redemption draws near. If He leaves us here another year, then we should watch next year at Trumpets. But on some Feast of Trumpets, the Trumpet blast will sound and the "wise virgins" will rise, and the foolish virgins will have to go where they buy and sell, because they weren't prepared to marry their Husband. If I proposed to my wife, and told her to be ready Saturday for me to come pick her up, and she refused to dress up, didn't fix her hair, wasn't peeking out the blinds waiting for me to drive up, I may honk the horn and she might not come out to meet me. Those people will be weeping and grinding their teeth at the opportunity they lost as they face the Beast and his head choppers. We should be LOOKING for His coming whether He comes or not.
I have a prediction. If you think there is no such thing as a "rapture", you won't be Raptured. If you think He will leave you here to suffer the Tribulation for 1260 days, you won't be Raptured. If you think He will wait until the Beast is killed to come get you, you won't be Raptured. Just as Noah was told to get in the Ark 7 days before the rain fell, God's children won't suffer one drop of His Wrath. The scoffers that didn't believe Noah, were left scratching and beating on the sides of the Ark as the rain fell. There is a direct connection between how much Bible study we choose to do, and how you will fare in the Last days. Lovers of God will be at the wedding as the Bride. Pew sitters that would rather fish or watch the NFL take a knee rather than assemble with others on the Sabbath, might say "I said the prayer when I was 12, so the God thing is taken care of", I'm not sure that is what God is looking for in a Bride. A servant does what they are told to do because they are told to do it, a lover does what they are supposed to do because they love their Lover. A servant can go to Heaven if they confess with their mouth Jesus is Lord, but Salvation and Rapture are 2 different things. Many marriages have failed because one or the other forgot their first love. Today, many lovers have become lukewarm thinking they have everything they need covered. The only church that is told they will miss the Tribulation is the one that loves the Lord with all their hearts, mind, soul, and strength, and loves their neighbor as themselves. If you aren't watching for His coming, do you really love His coming?