All modern faiths teach that homosexuality is a sin of some sort, some in different degrees.
The argument that if homosexuality is accepted then pedophilia, incest etc will also be accepted is fundamentally flawed.
If 2 people decide to follow a path such as homosexuality, then why is this act such a sin other than the word of God says it is.
Incest is evil because it has the ability to create new life, thus affecting the life of another potentially. Incest creates anomalies in the gene pool and may cause deformities in a child.
Pedophilia is evil (aka a sin) because it once again, affects the life of one who has no control over the situation. It has the potential to scar a young child for life, spread disease and otherwise cause many problems.
Now homosexuality while technically a sin to many religions, does not affect parties other than the 2 involved in the act. In most cases they are grown human beings, and have no explanation for why they feel this way....they just do. They are not evil.
Infact, many scientists believe there is a biological reason for homosexuality, much the same way there is reason for other conditions of the mind (both positive and negative). But the interesting thought lies again in the fact that it hurts no one in 99% of the cases.
The only argument one could present is that a child should not be raised by 2 men or 2 women as that goes against the will of God, or a code of widely accepted morality.
But in a world where there are children being raised by no men or no women (ie: street kids, wards of the state etc) this should not be a prime concern and if 2 people are willing to provide a loving home for an otherwise unloved child, who should stop them.
I in no way mean to "bash Islam", infact quite the contrary. I hold many of Islam's teachings very close to my heart despite what I may believe about religion.
In conjunction with reading the Koran and multiple other religious texts, I look forward to cruising these forums in a chance to gain a greater understanding about the great peaceful religion that is true Islam.
PS: No I myself am not gay.
An interesting read:
http://cas.bellarmine.edu/tietjen/RootWeb/npr_letters_on_the_biological_ba.htm