According to Wikipedia, this flag was designed around 1897 in Coney Island, probably by a Methodist minister. I lived in a Methodist camp town for ten years and I think I remember seeing it at their giant auditorium.
Big Whoop! Any two-bit minister can fashion a flag. The fact is there is no such thing as a Christian flag. And, even if we allow a flag to fly over the Stars and Stripes, it won’t take long for the Crescent and Star to fly over the Stars and Strips.