Why is Christmas celebrated on December 24Th and not the 25T h?

We all know what Christmas is all about (if you don't know, it's about celebrating the birth of our saviour Jesus Christ) and that's when we celebrate it.

It is highly unlikely that Jesus was born on the 25th of December. Scientists believe that Jesus was born in spring (probably March).

The Roman Empire expanded (as well you know) and so the Emperor became more and more powerful and well known. When Constantine became Christian, the rest of (or most of) the empire followed the Christian laws therefore scrapping the gods and goddesses of ancient Rome. When this happened some of the celebrations of the gods were replaced with celebrations of Jesus. Upon one of these dates (25th of December) was the festival of the Roman god Attis (this festival included feasting and drinking). Constantine thought that since they already celebrated the birth of one god, why not replace it with another? So came the date of the 25th of December for Christmas.

Christmas means the Mass of Christ.