Okay, in fairness, I've never seen the movie, and I've never read the book [nor will I ever see the movie nor will I ever read the book], but my layman's impression [from watching the controversy on the sidelines] was that the book/movie alleged that Jesus was "Ridin' Dirty" [to use a little Jeremiah Wright lingo] with Mary Magdalene, resulting in a race of superhuman creatures which had walked the earth in secrecy for 2000 years [until now].
And if my understanding of the basic plot is correct, and if you think that that doesn't amount to "anti-Christian propaganda", then you and I have reached a semantic impasse.
Your understanding is incorrect.
The proposition is that they were indeed married, (your offensive description to the contrary notwithstanding); for if they were not married, a royal bloodline could not be established as the historical/theatrical script proposed. I, as most citizens of our self-reliant Republic, could care less for royal bloodlines; but 2000 years ago those claims mattered.
As for "a race of superhuman creatures", that sounds odd since what made Christ exceptional was not his physical attributes that we all pass onto our own offspring, but his level of spiritual superiority which was unique to him.