Albert Barnes on Luke 24:26

Ought not Christ, &c. Ought not the Messiah. Was there not evidence that he would do it? and was it not indispensable that he should, in order to fulfil the prophecies? The necessity of his suffering these things referred to here was that it was foretold that he would. The reason why it was predicted, and why it was necessary that it should occur, was that it was proper that God should manifest his justice, and do honour to his law, and secure the due regard for his government, while he pardoned the guilty.

(s) Lk 24:46, Acts 17:3, He 9:22,23