Here "leads ... astray" is a metaphor for persuading someone to believe what is not true. AT: "deceives you ... they will deceive many people" (See: rc://en/ta/man/translate/figs-metaphor]])
Possible meanings are 1) "claiming my authority" or 2) "claiming that God sent them." (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-idiom]])