But he answered and said unto them, An evil and adulterous generation seeketh after a sign; and there shall no sign be given to it, but the sign of the prophet Jonas: An evil and adulterous generation - Or, race of people; for so γενεα should be translated here, and in most other places in the Gospels; for our Lord, in general, uses it to point out the Jewish people. This translation is a key to unlock some very obscure passages in the evangelists.
Seeketh after a sign - Or, seeketh another sign, (επιζητει), so I think this word should be translated. Our Lord had already given the Jews several signs; and here they desire sign upon sign.
Our Lord terms the Jews an adulterous race. Under the old covenant, the Jewish nation was represented as in a marriage contract with the Lord of hosts; as believers, in the new covenant, are represented as the spouse of Christ. All unfaithfulness and disobedience was considered as a breach of this marriage contract; hence the persons who were thus guilty are denominated adulterers and adulteresses. But, independently of this, there is the utmost proof, from their own writings, that in the time of our Lord they were most literally an adulterous race of people: for, at this very time, R. Jochanan ben Zacchai abrogated the trial by the bitter waters of jealousy, because so many were found to be thus criminal. See on John 8:3 (note).