Homosexuality? [Spoilers]

The soldier who claimed to love Knut, another man, was ultimately portrayed in the end of the movie as animated sin, so to speak. The movie is basically about sins, so does that suggest something about the soldier's homosexuality being sinful, or is it simply the idea of lusting? I read somewhere too that Knut was at one point "demonic" in a sense, and the solider fell in love with the "demon" and not necessarily Knut, so that act of falling in love with a demon would be the real sin, not homosexuality, which is my opinion, but still curious.