What is different about this one is the way it works through a couple hundred years of the history of theology to show how the church's treatment of gays is no different that its previous treatment of blacks and women. The Bible was misused to justify oppression of women and blacks and that pattern of misuse repeated to justify oppression of gays.
A pervasive theological viewpoint during the late 1700s was based on the Scottish Common Sense Philosophy. It said that we can look around us and see the reality of the world. The facts of any situation are obvious to everyone. The facts of nature are as plain as the facts of divine action recorded in the Bible. In addition, all peoples (at least people of the better classes) think the same way. It is this philosophy that is expressed in the famous American phrase, "We hold these truths to be self-evident."
The result of this philosophy was that Southern theologians looked around and saw that since slavery was practiced by everyone and since the Bible did not explicitly condemn it, God must support it. They don't see their own biases (after all, "everyone" thinks the way they do) and that God's will neatly matches those biases.
Abolitionists looked at the Bible differently. They started with the overall message of love and then applied that to every situation. John Rankin, a leading abolitionist, put it this way:
The whole Bible is opposed to slavery. The sacred volume is one grand scheme of benevolence. Beams of love and mercy emanate from every page, while the voice of justice denounces the oppressor, and speaks of his awful doom.Faulty theology allowed church people to portray blacks and women as less than human and to use those prejudices to oppress them. The church is using the exact same techniques to justify its oppression of gays today.