This last definition is what caught my attention. Isn't Messiah worthy of belief? Since He rose from the dead we know He can be trusted and is worthy of belief.
M-W provided this etymology for plausible:
Today the word "plausible” usually means “reasonable” or “believable,” but it once held the meanings "worthy of being applauded" and "approving." It comes to us from the Latin adjective "plausibilis" ("worthy of applause"), which in turn derives from the verb "plaudere," meaning "to applaud or clap.”
We should consider Messiah worthy of all applause [praise].
