Luke 4:35 ASV

You have to wonder, why would Jesus tell the demon to be quiet after the demon just stated that he knew who Jesus really was. Was it because Jesus knew that if the demon told people then it would mean they would only believe in him because of signs and miracles and not out of faith? Or was it because he knew what had to be done to save a dying world, and this could not be accomplished if everyone already knew who he was?