Jesus condemns as evil and adulterous those seeking a sign in unbelief. God can be willing to give a sign: (Judges 6:17–24 (Gideon); 2 Kings 20:8–11 (Hezekiah); Isaiah 7:10–14 (Ahaz). The problem was that the Pharisees refused to believe the signs they had already seen. The word evil
recalls Matthew 12:34–37. This generation (of scribes and Pharisees), who rejects John the Baptist and challenges Jesus, is evil in their unbelief. They are also adulterous,
which echoes the Old Testament, which often shows unfaithfulness to the Lord as adultery. Demanding a special sign shows this generation as fickle and unfaithful to God. The words evil and adulterous
do not mean a general moral flaw, but a religious hostility to God’s prophet and Messiah. Because Jesus is the Lord himself, he can rightly call their attitude evil and adulterous, in words of judgment that reflect the majesty of the One who speaks them.
Jesus condemns as evil and adulterous those seeking for a sign because of the state of their heart from which the request itself originated. In principle, God is not unwilling to give a sign: see Judges 6:17–24 (Gideon), 2 Kings 20:8–11 (Hezekiah), and Isaiah 7:10–14 (Ahaz), and many other such instances. The problem, however, was that the Pharisees were unwilling to believe the signs they were already given.1
The word evil
recalls Matthew 12:34–37. This generation (of scribes and Pharisees), who rejects John the Baptist and challenges Jesus, is evil because of this unbelief. In addition, they are also adulterous,
a description which recalls the Old Testament, where unfaithfulness to the Lord is often portrayed as adultery. By demanding a special sign, this generation shows itself to be capricious and unfaithful to God. The words evil and adulterous
do not refer to a general moral deficiency but rather to a religious opposition to God’s prophet of repentance and God’s anointed Son of David. Because Jesus truly is the Lord himself, he can rightly call their attitude evil and adulterous, and these words of judgment also reflect the majesty of the one who speaks them.2
39 But he answered them, “An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of the prophet Jonah.