@skylarwhite. Comparing the issue of slavery to the issue of homosexuality is an informal fallacy. Yes I concede that the mistreatment of black people was tenuously justified through scripture. The curse of Ham (Genisis 9:20-7), it was later interpreted that Ham was black (not really solidly from a scriptural standpoint), thus justifying the curse of being made "servant of servants" being applied to a whole race.
Furthermore the manner of slavery as practiced in the American colonies is expressly forbidden in the bible (Exodus 21:16) kidnapping and selling people into slavery is a crime punishable by death. In addition to other passages relating to how slaves should be treaded which was most certainly not adhered to in the Americas.
Homosexuality however does not enjoy much in the way of pro-homosexual passages. The best I have been able to come up with is by going back to the original Greek (Romans 1:18-27). This is ironically one of the go-to passages for anti-homosexual arguments. In verse 26 the words φυσικὴν χρῆσιν are translated to mean natural function, however a more accurate in my view definition of φυσικὴν means born nature or born into. In other words the nature one is created with. Therefore if one is born homosexual it would be against God to try to be anything else.
In that passage Paul was censuring Christian converts who had lapsed back into Pagan practises that involved sexual rites with people engaging in sexual activity which was according to Paul against their nature (which if they were heterosexual it would have been). However even if that IS the correct interpretation it still does not provide us with biblical references in support of Gay marriage, which is where drawing parallels to the slavery/racism in America falls down.
There are a great many non-homophobic Christians that are wrestling with precisely this issue, when what ultimately needs to happen is a reexamination of what a marriage precisely is in the eyes of God, and eventually a redefinition of what it means to us as necessary. These are weighty issues for all concerned that require sound scholarship, compassion and humility. NOT just knee-jerk responses by either side, or meddling from the courts.
I know it might make it easy to draw a black and white line in your head. Clump all the people who don't agree with you as in the wrong, intolerant homophobes (if your are pro-church gay weddings), or as in the wrong, and wanting to destroy the Christian definition of marriage and family (if you are anti), but really those are just gross oversimplifications of the issues at stake, and both extremes go against the beating heart of love, faith & hope that should be at the centre of any Christian Church.