No, I agree that’s what Side B Christians, who are a tiny minority of LGB people who endorse hateful, conservative Christian theology, say they believe. Esther, the progressive Christian who wrote the article, does not believe what Side B Christians believe. Progressive Christians (think Canadian Anglicans, Episcopalians, UCC members, and UMC Christians who are staying in the denomination while a minority of homophobic bigots take their ball and leave, etc…) do not believe the Bible “makes very clear” that gay Christians sin when they have sex. In fact, it might surprise you to know that your argument about Biblical literalism wouldn’t move most progressive Christians, whose beliefs don’t center around Biblical clarity, or (for the most part) around textualism in general. Progressive Christians in general (who exist in very large numbers in the U.S.) wouldn’t even understand your idea that they are “supposed” to believe something.
For example, see my recent story about a UCC congregation in a little Ohio town that stood up to Proud Boys, Patriot Front members and conservative cops:
