I guess it’s consent. The master/deity or their aide comes to the servant and tells them of master’s will, the great plan. The servant says, yeah, okay.

Yet another fail in writing. Why not make it so God and Gabriel give her the choice, and she adamantly agrees? Remove all doubt from the story’s plot. Or better yet, add some drama, have Mary unsure, and Gabriel explains the importance (not that it’s already planned, but why her choice is key to the direction of salvation and all that). And she with some thought decides to do it.

Oh, right… that would give a woman some agency. Never mind.