Regis Nicoll's exellent article, God Made Me Gay, begins:
It includes celebrities (Ellen DeGeneres, Ricky Martin, Clay Aiken), politicians (Rep. Barney Frank, Gov. Jim McGreevey, John Berry), and Christian artists like Jennifer Knapp and Ray Boltz. It is the growing group of high-profile people who have broken the silence about their homosexuality. Many of their stories share telling similarities. . . .
... Setting aside the moral arguments about same-sex desire, from physiological considerations alone, it is disordered because it is contrary to the function its “form” is intended to serve.
Human sexuality is uniquely designed to satisfy an essential biological purpose: reproduction. In a very real way, when a husband and wife come together they form a single biological unit through their “hand-in-glove” complementarity. It is a function that same-sex individuals are incapable of accomplishing. They can only transmogrify the sex act to indulge in sensual gratification.
Sex involves pleasure but, as C.S. Lewis once pointed out, that is no more the purpose of sex than it is the purpose of eating. In both cases, sensual enjoyment is the byproduct of functions that are indispensible to life and the continuation of the species.
Nicoll covers a lot more ground, and he does it well.