The Christian versus the libertarian in me.

From a secular point of view, it is difficult to see how homosexuality can be criticised - and the libertarian part of me finds arguments against it rather unconvincing BUT when we take the Epistle to the Romans [inter al] into account, we find that God has a view that the practice of homosexuality is sinful.
It is not the view of mankind which should prevail but that found running as a theme throughout both testaments - God's view!

ROMANS: 7:7. What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet.

Homosexuality and covetousness therefore share a common base. It is through the Law that we are able to recognise sin - even where this may not be immediately obvious to us.