It was created by Joe Casey, though Uncanny X-Men writer Chuck Austen featured the hate group in a controversial storyline which involved an elaborate plan to install the recently ordained Nightcrawler as Pope and stage a false Rapture using incendiary communion wafers as part of a plot to topple the Catholic Church.
They are the more radical offshoot of the Friends of Humanity anti-mutant group, but with a religious discourse, similar to the Purifiers, the followers of Reverend William Stryker.
The Church of Humanity is similar to real-life white supremacist religious groups such as the Christian Identity movement.
[1] The Church of Humanity crucified some mutants on the lawn on the X-Mansion including Skin, Magma and Jubilee.
Archangel used his healing blood to revive Magma and Jubilee, but, apparently, Skin, among several others didn't have the same luck.