A Formal Argument against the Permissibility of Homosexual Activity

Many people wish to do as God commands in Scripture, yet the modern mind is finding it increasingly difficult to understand why God would forbid homosexual acts.  Even granting that we should do as God commands just because God commands it, it's still helpful for us to understand why God would command as he does.  I decided to create a formal reproduction of the argument Alexander Pruss makes in his book One Body against homosexual activity.   Attempting to answer such curiosity to these questions can solidify our confidence in the rightness of God's commands and further reveal the nature of God's goodness.  I think the argument as it stands goes someway towards establishing why God prohibits homosexuality.   

I'm not the greatest at symbolic logic, so the symbolization is rough.  But it is valid.  So if the premises are true, the conclusion must follow.  The argument has controversial premises ((3.) being the most controversial? a couple of others, too), but I think they can be supported.  I might provide justification for them in a later post.  I do want to provide an explanatory note for premise (3.) at the offset, however.  When I use the phrase "one body" I mean something very precise and concrete: Only two opposite sex-bodies can join together in such a way that their bodies strive biologically towards the same goal and thus become one body.  For all of our biological functions human individuals form complete wholes save one.  We have a complete digestive system.  A complete breathing apparatus.  The only biological function that requires another individual to complete is reproduction.  Biology is the underlying good of many different human goods. The pleasure of eating is undergirded by the biological good of nourishment. Even the prohibition against murder is based in biology. So it shouldn't surprise us that biology would play such an important role.

1. If a pleasure is divorced from its underlying good, then that pleasure induces deception and undermines integrity. 
∀x(Dx⊃~Ix) 
2. Any intentional behavior that induces deception and undermines integrity is wrong. 
∀x(~Ix⊃Wx) 
3. The relevant underlying good of sexual behavior is one body union. 
∀x((~Dx&Sx)⊃Ox) 
4. Homosexual behavior cannot achieve one body union. 
∀x(Hx⊃Sx)&~∃y(Hy&Oy) 
5. Homosexual behavior induces the relevant pleasure without the underlying good. 
∀x(Hx⊃Dx) 
6. So homosexual behavior induces deception and undermines integrity. 
∀x(Hx⊃~Ix) 
7. So homosexual behavior is wrong.
 (∀x(Hx⊃Wx))