He saved others - It does not seem probable that they meant to admit that he had actually saved others, but only that he “pretended” to save them from death by miracles, or that he claimed to be the Messiah, and thus affirmed that he “could” save them. This is, therefore, cutting irony.
If he be the King of Israel ... - It may seem strange to some that Jesus did not vindicate by a miracle his claims to be the Messiah, and come down from the cross. But the time had come for him to make an atonement. He had given full and sufficient proof that he was the Christ. Those who had rejected him, and who mocked and taunted him, would have been little likely to admit his claims if he had come down from the cross, since they had set at naught all his other miracles. They said this for the purpose of insult; and Jesus chose rather to suffer, though his character was assailed, than to work a new miracle for their gratification. He had foretold his death, and the time had come; and now, amid revilings, and gibes, and curses, and the severe sarcasms of an angry and apparently triumphant priesthood, he chose to die for the sins of the world. To this they added “insult” to God, profanely calling upon him to interpose by miracle and save him, if he was his friend; and all this when their prophets had foretold this very scene, and when they were fulfilling the predictions of their own Scriptures. See the Isaiah 53 notes, and Daniel 9:24-27 notes. So wonderful is the way by which God causes His word to be fulfilled.