The Jews is Jesus' time were watching in great anticipation for some sign which would indicate when the Messiah would appear to establish the kingdom of God. The Pharisees' question on this matter was intended to test Jesus since they did not accept him as the Messiah. Jesus surprised them with the answer that the kingdom or reign of God was already here! Jesus spoke of the coming of God's kingdom as both a present event and an event which would be manifested at the end of time.

Why did Jesus associate lightning with the "Day of the Lord"? In the arid climate of Palestine, storms were infrequent and seasonal. They appeared suddenly and unexpectedly, seemingly out of nowhere, covering everthing in thick darkness. With little or no warning lightning filled the sky with its piercing flashes of flaming light. Jesus warned the Pharisees that the "Son of man" (a title for the Messiah given in the Book of Daniel 7:13-15) would come in like manner, quite suddenly and unexpectedly, on the clouds of heaven to bring God's judgment on the "Day of the Lord." No special sign will be needed to announce his appearance. Nor will his presence and power be veiled or hidden, but all will recognize him as clearly as the lightning in the sky.