I'd actually feel sorry for anyone who went because of the sex scenes because they only take up a tiny proportion of the film and apart from the disturbing initial scene (and maybe final shot) they are more likely to amuse or embarrass, not titillate in any way. 

Imagine the hard work of sitting through a difficult film made up of mostly slow panning shots and a laborious weak plot just for a flash of flesh (not exactly attractive flesh either)!

I'm not religious but found the religious aspect of the film to be the most satisfying part, religious devotion has an incredible hold over peoples lives and the scenes of the pilgrims and of Marcos seeking redemption are by far the strongest in the whole film.

I'd say for anyone wanting a flesh fest, stick with any of the thousands of porn films out there, Battle in Heaven will be too much effort for you.

Cheers Trev.