The most important sign that they missed was the Messiah’s coming and revealing his glory to men (John 1:14). He himself was the sign from heaven (Luke 2:34). His ministry showed that the fullness of time had come (Galatians 4:4), so Jesus had already proved his divine authority in the way they now pressed him to do (Matthew 16:1). Unbelief, however, prevented them from seeing these signs, so Jesus’ reply is not an excuse for not giving a sign, but a rebuke of the Pharisees and Sadducees’ blindness.
The most important sign that they missed was that the Messiah had come and revealed his glory to men (John 1:14). He himself was the great sign from heaven (Luke 2:34). Through his ministry it was evident that the fullness of time had come (Galatians 4:4). In all of this, Jesus had already fully legitimized his divine authority in the way they now requested him to do (Matthew 16:1). Unbelief, however, prevented the Pharisees and Sadducees from recognizing these signs, and they failed to draw the right conclusion from them. Jesus’ response is therefore not an excuse for not giving a sign, but rather an accusation against the Pharisees and Sadducees for not recognizing the signs.1
2 He answered them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’