I think that they are referring to the somewhat adversarial attitude of the comments in this thread. I think that a religious person, especially a self identifying Christian, would feel a bit uncomfortable reading these comments.
Merriam-Webster on "militant" (2nd definition): aggressively active (as in a cause) : combative; militant conservationists; a militant attitude
Washington was a pretty bad president if you were Haudenosaunee (Six Nations Iroquois).