Probably the most reasonable ones are the following:

a. The demons knew that Jesus was the Messiah. But if the people were to believe this and to act upon it, they might start a movement to make Jesus a king. Cf. John 6:15. And, of course, Jesus does not want this at all.

b. Closely connected with the first is the reasoning that, due to the expected opposition from the side of Jesus’ enemies, any public acknowledgment (at this time) of Jesus as the Messiah would in all probability have brought about a premature crisis. Though it is true that Jesus “from his throne on high came into this world to die,” he must not die immediately but at the appointed time.

c. During the period of Jesus’ humiliation any proclamation of his identity as the Messiah would have been in conflict with the mandate he had to fulfil until the day of his resurrection. This is the position of H. N. Ridderbos, who offers as proof such passages as Mark 9:9, 30, 31.

Which of these three answers is the right one? Is there, perhaps, an element of truth in all three? Or is there still a better answer? Since Jesus himself never gave us any further explanation, it is probably well for us not to delve any more deeply into this subject.

Source: Hendriksen, W., & Kistemaker, S. J. 1953-2001. Vol. 11: New Testament commentary : Exposition of the Gospel According to Luke. Accompanying biblical text is author's translation. New Testament Commentary . Baker Book House: Grand Rapids