I hate one-liners, dead horses, logical fallacies, and "here's something similar so this applies to". That in mind, I'm going to commit all of those sins.
For centuries, it was understood, clearly, that the will of God was for women to be subservient to men, even silent, unemployed, and uneducated.
For centuries, it was understood that God favored the white man and gave him the authority over the black man and women, including owning him. Slavery was not something Christians thought immoral. In fact, for many Christians, slavery was vehemently defended in the legislature as a Christian teaching. After slavery, segregation.
It was understood for centuries that if a person had a horrible, disfiguring disease it was because of sin, one they or their parents had committed, and they were being punished.
For centuries, it was understood that only those born in a certain country, to certain parents, were worthy of the kingdom of God.
There was a time the Bible 'clearly' said that it was a fathers duty to stone his daughter if she was unfaithful to him or her husband (in the context of that culture, a woman was faithful to her father by being a virgin, he 'owned' her sexuality until such a time as he permitted some other man to have it)
There was a time when the Bible 'clearly' stated that touching a woman during her period was a grave sin and if she failed to prevent you from doing so, she was to face grave punishment.
There was a time when the Bible 'clearly' said the Sun was heaven, and that the Sun revolved around the earth.
God didn't change, the scripture didn't change. God's will didn't change. We didn't re-translate the Bible or make some sort of big theological breakthrough. We didn't unearth some ancient scripture and Jesus didn't pop back through a cloud to correct us. Over time, culture began to shift to the will of God. It began to reject various injustices that turned out to be powerful humans trying to control less powerful humans, and using God to do it. Jesus himself 'called out' a number of the Jewish laws.
If you have a different opinion about human sexuality that's fine. Some of my dear friends and colleagues would tell me to differ in opinion (one way or another) is inexcusable; but as someone who has been on both sides of that fence I'd feel like I was a hypocrite if I did the same. But I would encourage you to take a step back and ask yourself if folks on this side of the issue of human sexuality are actually trying to make the Bible fit culture; or if they believe they are trying to make culture fit the Bible? Some of us don't find homosexuality to be a "clear sin", in that sense. Sure, in many english translations; but breaking down the historic, contextual text the line is a little fuzzier.
I'm not asking you to change your opinion, just your frame of mind. I think that there's a disconnect when people on the traditional side think that those of us who struggle with the issue and wrestle with whether the church has it 'right', are admitting that it's a sin but want the rules to change to fit culture; because overwhelmingly that's not the case. While culture might affect their perspective (it would be naiive to think otherwise; and that's true for both sides of the coin); most people I know aren't really all that concerned with culture; but Biblical obedience. They've seen examples of people trying to use the Bible to hurt people and they think this is one of those times; and that the Bible supports equality.
There ARE those who say the Bible is irrelevant, but that's not been the case of United Methodists I know who are in support of LGBT Equality. One of the things that makes me proud to be a UM is that even those who hold positions that are in conflict with the UMC or even the broader Christian church do so with a high understanding of Biblical authority and the ability to defend their position using scripture, tradition, reason and experience. As opposed to perhaps some Fundamentalists I know who simply defend their position with literal readings of texts and proof-texting (the same things that justified slavery, poor treatment of women, etc.); or folks on the far left who simply say "Well the Bible is irrelevant today, and is just a guidebook". Because I don't believe either of those things, and I'm glad there are so many others who are with me in both holding a high view of scripture; and being comfortable asking if the Bible is as "clear" as so many people tell us (because it's been 'clear' many times before. And suddenly 'clear' in the complete opposite.)