Salam Alaikum:
I also saw the movie on Friday night and it is nothing more than fiction. There are some facts in there about different things, but the rest is all theory, speculation and what ifs. For me, it left the conclusion up to the viewer. Muslims and Christians might be offended for different reasons. ie. Muslims offended at the suggestion Jesus, pbuh, was married and fathered a child, and Christians for the simple fact it would send Christianity as it is known today into a major tail spin. Athiests and Agnostics may choose to accept it or prefer to scrutinize further. Nothing in the movie, in my opinion, tried to pass this off as factual.
I actually enjoyed the movie, but nothing wowed me.
There has always been questions about the codes used in Da Vinci's paintings....this movie portrayed one of many theories for various reasons. ie. the lack of a cup at the last supper, the symbols created in paintings, etc. They took these centuries old questions and created a hypothetical situation. There is absolutely no basis in fact and it never makes that claim.
I see nothing wrong with trying to find answers through hypothetical situations. For me, this particular situation doesn't work for numerous reasons, someone else may feel different.
In the end, it is only a fictional movie and nothing more. I went with my christian friend and she felt the same. But, it did give us lots to talk about later and gave me an opportunity to tell her more about Islamic belief.
Wasalam,
Hana