There is not a lot of evidence they wanted it to coincide with a pagan festival. In fact, keep this in mind, Christians were willing to be murdered to point out the fact they were nothing like pagans. The dating of Christmas has more Jewish roots. In Jewish tradition, they celebrated the conception of their holy figures around the time (if not on the date) of their conception (As is said in the article). Christians celebrate the Annunciation (the day Gabriel announced to Mary that she would conceive) around Easter, and sometimes the two days actually land on the same exact day. It had literally nothing to do with some random pagan festival.

The traditions of Christmas that have to do with Christmas tree's, etc... More have to do with more recent developments of celebration. In the case of Christmas tree's they didn't see widespread popularity until the 1800's in England, and THey weren't really used in Germany either until the 1500's, so the connection to paganism is tenuous at best.

Also, as for the difference between the December 25th and January 7th dating (According to that article). It was not because of some "true date" it has to do with the fact that BOTH celebrated it on the same day, and later the West adopted the Gregorian calendar, those in the East still used (and some still do) use the (revised) Julian calendar, so really there's no actual difference in the dating other than calendar use.

As for their discussion on Saint Nicholas, I think their research is lacking. There is historical proof of Saint Nicholas existing (they neglect to point out that he was a Bishop). He is recorded as attending the First Council of Nicaea.

One further thing to note, outside of larger councils, there were no huge pronouncements (except when there were slight disagreements, as in the dating Easter). There wasn't some council of Church leaders who went around dictating such things. It was local custom that followed the calendar and what had been passed down to them. So it's not as if the pope could make a decree and everyone would follow. THey would see as others were doing and (sometimes) follow suit.

So I think it's a pretty slim way of looking at things for them to say that there was some pagan reason for changing from Jan. 6 to December 25, and more just natural ones.

What other accusations of paganism are there?