But why? Why do you think Keldorn would see anything wrong with homosexuality at all?
I suppose you're going to want proof before anyone comes to the conclusion that Keldorn and/or his order may not endorse homosexuality?
May not endorse? You were refuting someone claiming Keldorn endorses homosexuality? No...no, you said Keldorn, and every paladin order, would object to it. You made the claim. Support it.
I can sense the approaching footsteps of an all too familiar line of reasoning: since there's no proof in the game that Keldorn denounces homosexuality, this can only mean he welcomes it with open arms! I never tire of that logic.
That's probably why you use that kind of logic so much yourself. And it's the only kind I've ever seen you use: The game doesn't say one way or another, so your assumptions are logical and anyone who disagrees with you is Wrong because you say so.
Logical: The game doesn't say one way or another whether Keldorn objects to homosexuality. Therefore, if anyone wishes to assert that he does, or that he doesn't, that person should support that claim. The game doesn't say one way or the other whether paladins in general object to homosexuality. Therefore, if anyone wishes to claim that they do, or that they don't, that person should support that claim.
If you use the real world as an example, do you really expect no one in Faerun to take a religious or moral stance against homosexuality?
Real-world religious objections to homosexuality are based on a god who 1) has, in
AD&D terms, a debatable alignment and 2) doesn't speak directly to his followers very often if at all, leaving his followers to interpret his words. Faerun deities are way different; none of them are even arguably perfect, but they communicate clearly with their followers. If the Tormites believe Torm objects to homosexuality, then Torm does object to homosexuality; unlike the real world, there is no room for misunderstanding. Keldorn would only object to homosexuality on religious grounds if Torm actually objects to homosexuality, and the only reason you have for thinking Torm might, apparently, is "Yahweh does."
Looking only at the claim that every paladin order would object to homosexuality, and pushing Keldorn aside for the moment, I would contend that "required Lawful Good alignment, if they ever commit an evil act they Fall" is incompatible with "institutionalized bigotry." Real-world religions have nothing like that--no detectable alignments, no Falling and losing flashy magical powers.
That said, no, I don't think no one in Faerun would object to homosexuality--as I hinted above, I would expect Bane and Lolth, for starters, to have strict prohibitions against homosexuality. Homophobia is just unlikely to be any part of the doctrine of a non-evil god, and Torm is a Lawful Good god.
Keldorn's order was strict enough to severely punish his wife's infedelity
Keldorn's order? Keldorn's order wasn't involved with his wife's infidelity.