In the New Testament Book of Revelation, Michael leads his angels against the dragon ("the Devil and Satan") and his angels during the war in heaven[9] where he defeats the dragon. In the Epistle of Jude, Michael is specifically referred to as "the archangel Michael". Sanctuaries to Michael were built by Christians in the 4th century, when he was first seen as a healing angel. Over time his role became one of a protector and the leader of the heavenly host against the forces of evil. https://en.wikipedia.org/wiki/Michael_(archangel)

The verse from Flynn can be found here, half way down the page in bold.

https://www.summitlighthouse.org/pearls/1984pows/841001MI.html