They do not celebrate Christian holidays.
I cant blame them...Christianity is full of pagan doctrines eternal hell fire being one of them
Part of the problem is that the Jehovah's Witnesses are a late comers to Christianity.....established around the late 19th century.
The other problem is that they do not teach history in Church....not even Christian history. The Apostles were Jews and the early Christians were Jewish-Christians. Most of the Jews rejected Christ. Paul's ministry was to the Pagans .... Pagan converts to Christianity .... Gentiles. Within the first century or shortly after Gentiles dominated Christianity and then completely took over the helm of the Church.
The Gentiles....coming from many regions and countries....Believed in Christ but they came from different cultures and they did not abandons those cultures. And they still celebrated certain days....and they were Pagan....but as time went on they Christianized these holidays. Then Emperor Constantine consolidated the holidays.
Now I think Yeshua knew all about what was going to happen and if He did not want it, He would not have commissioned Paul to start his ministry to the Pagans. Yeshua did not have to do that, He did not have to offer salvation to the Pagans. Then because the Jewish-Christians did not last long....Christianity might have died out....but that is another story.
The Jehovah's Witnesses attitude toward Christian holidays is one of many things that put them in the column under anti-Christ.... anti-Christian....and more in line with Judaism.
They do not require a Christian Wedding ceremony.
Well there certainly is now and the Protestants were the ones that required it. But people can plan ceremonies as they wish and Christians get married in a church. And that is my point.
And there is more than one model for the Trinity. Jehovah's Witnesses object to the Trinity because the want to demean Christ.
The Jehovah's Witnesses view of the covenant....I do not think that it is a set model. I participated in a few interventions to try to save people from the Jehovah's Witnesses and it did not seem that they all believed the same way about the new covenant. Best I can tell the Jehovah's Witnesses do not believe we are in the new covenant yet.