You are playing dishonest games with words.
Christianity is either true or else it is “based on pagan beliefs”. It can’t be both and you know it.
Christians believe what we do because we believe that the events described in our holy scriptures are true. That is, we believe they actually happened as described.
Apparently you do not believe this and that is your choice. But why do you come on here, call Christianity a lie, and then deny doing so? What compels you to such deceit?
Go do your research and find out the origins of Christianity.
Are you aware that the early New England colonists such as the Pilgrims (and I think Puritans) did not celebrate Christmas and Easter. Why would they not celebrate such Christian holidays?
Again, all I ask is that you do your own research.