JW believe Jesus is Michael the Archangel manifest in the flesh.
The bible says that if any come to you not claiming Jesus is the Word of God or Logos manifest in the flesh, let them be accursed. In essence they have a different Christ. That being said, like any cult organization or church that falls into false doctrines and traditions, a broken clock can be right twice a day
. It doesn't mean that the organization itself is right or in God.
Regarding "Holy" days or holidays, I know of 7 major ones that are biblical. I also know a few of the minor feasts that the Jewish people had established as milestones for what God had done for them.
As part of our Sanctification process, for born again believers it is foolish for any of us to do something without first examining what it is that we do. The bible tells us to seek what is pleasing to the Lord. The born again believer has an imperative to test all things and see if God is pleased with what it is that we are about to do. So with ANYTHING that we do including the celebration of "Christmas" we are asked to see what God says about the subject from OT to NT to find out if it's something He wants us to do. I'd examine the celebrations and traditions and compare them to scripture. I'd examine the circumstances of the advent and compare them to scripture. Then ask the Lord to guide your decision about the subject. Regarding Christ-mass, the Lord has already had me make my decision regarding this day. However, we all have a choice to make
. Just remember, when we worship Him, we worship Him in both Spirit and in Truth.