Haven't read the thread but just answering the OP:
Many Christians claim that homosexuality is immoral because sections of the Bible say it is, but this brings up a larger question. What gets deemed "immoral"?
As a general rule of thumb, in Xianity whatever is idolatrous (shows that a person is worshipping something/someone besides God) is immoral.
This is an extremely dense concept. An individual Xian is responsible for applying it, in context, across his whole life: for example, it includes the idea that human beings are made in God's image, and are precious to God, and should be treated with honour--so adultery and fornication (having sex outside of marriage) is a sin, since both sins damage human relationships.
Also, deciding that God meant "a man and a man" rather than "a man and a woman" = marriage, because it's more convenient and culturally logical to do so, would be an idolatrous action.
Another e.g.: there are times that a Xian will go to war in order to protect others, but in other circumstances, that same Xian may refuse to participate in armed conflict in order to save lives.
After all the Bible also says that shellfish is immoral but Christians don't impose bans on that.
Please don't forget that Xians are not bound by the Old Testament, but by the New Testament. Dietary restrictions were a feature of the Old Testament, which was binding only for the Jewish people (and those who converted to Judaism before Jesus' death).
The New Testament was extended to
all peoples, including the Gentiles (i.e., those who are not Jewish). The dietary and cleanliness/holiness prohibitions (e.g. physical circumcision of boys) were specifically lifted in the NT, since God ordained that the focus be shifted from external to internal obedience. See Mark 7 for more information on this. There are other passages that deal with this too.
Also why is it that God's morals seem to line up with the morals of the people that wrote the Bible?
Well... if you believe that God directly inspired the writers of the Bible to write what they did, then that would answer your question.
If you believe that the Biblical writers wrote what they did to control people, etc. according to their own personal morality... well then, why ask the question, since you already know the answer?
And gee, did they ever get their own way, those horrid Biblical writers. Writing all those nasty, controlling things so they could live a life of fame, fortune and comfort--
uh... I mean.... live their lives in material poverty and terrible hardship, and later die criminals' deaths, which could have been avoided had they recanted...
hmmm.
/<gentle sarcasm>