MT 16:20 Then He warned the disciples that they should tell no one that He was the Christ.
The Lord Jesus prohibited His disciples here from telling others that He was the Christ because of the unbelieving condition of Israel. Israel, as a nation, reached a stage wherein they finally decided to reject the Lord Jesus. Further evangelism was futile.
MT 16:20 Then He warned the disciples that they should tell no one that He was the Christ.
MT 16:21 From that time Jesus began to show His disciples that He must go to Jerusalem, and suffer many things from the elders and chief priests and scribes, and be killed, and be raised up on the third day.
Israel only wanted Him for the material benefits that they can reap out of Him. They only wanted Him as their political King. They never saw the need to be saved and receive Him as their Savior.