βYour affectionate uncle, Screwtapeβ
I cannot express how much I dislike the St. Michael Prayer after Mass. it is so, so jarring to me every time.
To say nothing of the intent/content of the prayer, the language, and repetition and prominence given to it breed a sense of paranoia and cynicism. Instead of going out to evangelize the world, everyone is ready to go to war with it.
This prayer is totally fine in private devotion. It does not belong in the liturgy (or effectively within the liturgy, when it is said after the final blessing but before the recessional hymn)