The first advent of Jesus Christ guarantees His second advent. There are two reasons for this assertion. Jesus did not fulfill all that the Old Testament prophets predicted; therefore, He must return to fulfill the rest. The second reason is Jesus Himself predicted His second advent. He told His disciples on the night before His death, “And if I go and prepare a place for you, I will come again and receive you to Myself; that where I am, there you may be also” (John 14:3).
Like His first advent, no one knows when Jesus will come the second time. In the first verse of this text (Mat 24:36-42), Jesus said, “But of that day and hour no one knows, not even the angels of heaven, but My Father only.” Like in the days before the Noahic flood, the world will not expect the coming of the Lord. But we His people must live in constant expectation and readiness for His return. Jesus said at the end of this passage, “Watch therefore, for you do not know what hour your Lord is coming.”