Foxman, et al., didn't criticize Gibson's movie as sacrilege .... heck, I've seen dozens of movies that made light of Jewish religious ceremonies and nobody bitched about that aspect of them .... Gibson's movie is being criticized because of fears it will provoke ethnic hatreds.
Nobody feared that 40 Days - 40 Nights , a rather pointless sex comedy, would do that much damage. And frankly Jewish organizations are hardly the authorities for what is or isn't an acceptably solemn view of Lent.
I think it's more than that. Gibson's critics fear that "The Passion of the Christ" will create both more Christians and more passionate ones (including some who will actively oppose Hollywood's attempts to turn America into the Weimar Republic).