Shall the 'christians' celebrate?

This is false, that's all I'll say. A different name MEANS a different celebration. 

Christian Feasts are Christian. Not Jewish or Pagan.

I suppose we Christians CAN celebrate the ancient Israelite festivals if we like.  But we have no obligation or requirement or duty to do so.

By the way, read Colossians 2:16-23, which addresses this question.

Celebration is in the mind of the celebrant.  

The whole country doesn't celebrate my birthday on July 4th.

Romans 14:5, "One person regards one day above another, another regards every day alike. Each person must be fully convinced in his own mind. He who observes the day, observes it for the Lord."

We have liberality in Christ. You can celebrate both or none if you wish.

Colossians 2 "Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day."

You're not required to follow any tradition of man, but if you're a gentile then why would you practice jewish holidays, God made you a gentile

no we are not Jewish....

No pagan ever celebrated the birth of Jesus, fool.