It is important to understand that the Bible does not say that homosexuality is a sin, but rather it says that homosexual sex is a sin. Homosexuality just means that someone has the temptation to sin in a specific area and while I don't struggle with that particular temptation, I do struggle with the temptation to sin in other areas. However, all sin is wrong, so the fact that we still sin doesn't justify any else's sin. Furthermore, the Bible does not say that we should treat anyone differently just because they are attracted to someone of the same gender, but if someone is caught in sin, but Bible does instruct us to gently restore them.
I think there is good evidence that homosexuality is at least caused in part by nurture, such as by childhood sexual abuse. If people didn't think that our desires influenced by advertising, then it wouldn't be a billion dollar industry. However, the issue of whether or not homosexuality is genetic is completely irrelevant because we are still responsible for the choice that we make. Alcoholism is also genetic, which can explain someone's alcoholism, but doesn't excuse. They are still responsible for their actions.
The comparison between Chick-Fil-A and the KKK is completely and utterly absurd. People are not homophobic racist bigots just because they disagree with someone's political position. In Muslim countries they kill homosexuals, so it is very strange to see the same people who compare Chik-Fil-A with the KKK turn around and supports Muslims.
So we can be friends with homosexuals, but no one who condones another person's sin is their ally.