These renegade mutants follow Magneto as if he were and shepherd and they the herd. They have adopted his belief that humans and mutants cannot peacefully coexist and have sworn to live and die by his command.

noun

1. Roman Catholic Church - historically, a member of the highest of the four minor orders, whose duty it was to serve, especially at Mass, in minor ways; now, a person officially appointed or delegated to serve; an altar boy
2. an attendant; follower; helper

Magneto
mutant