Because it was to be doubted, lest, being cast down with despair, they should refuse his doctrine, he doth a little lift them up. We must so temper our sermons that they may profit the hearers, for unless there be some hope of pardon left, the terror and fear of punishment doth harden men's hearts with stubbornness; for that of David is true, That we fear the Lord when we perceive that he is unto us favorable, and easy to be pacified, (Psalm 130:4.) Thus doth Peter lessen the sin of his nation, because of their ignorance; for it had been impossible for them to have suffered and endured this conscience, if they had denied the Son of God, and delivered him to be slain, wittingly and willingly; and yet will he not flatter them, when as he saith that they did it through ignorance; but he doth only somewhat mitigate his speech, lest they should be overwhelmed and swallowed up of despair. Again, we must not so take the words as if the people did sin simply of ignorance, for under this there did lie hid hypocrisy; but as wickedness or ignorance doth abound, the action is named of the one or the other. This is, therefore, Peter's meaning, that they did it rather through error and a blind zeal, than through any determined wickedness; but a question may be moved here, if ally man have offended wittingly and willingly, whether he shall surely fall into despair or not? I answer, that he doth not make mention in this place of all manner of sin; but only of the denying of Christ, and of the extinguishing of the grace of God, so much as in them did lie. If any man be desirous to know more concerning this, he may read the first chapter of the First Epistle to Timothy, (1-Timothy 1:13.) As did also your rulers. First, this seemeth to be an improper comparison, for the scribes and the priests were carried headlong with a wonderful madness, and they were full of wicked unfaithfulness; [1] but the perverse study and zeal of the law did prick forward the people. Again, the people were incensed against Christ, inasmuch as their rulers did provoke them thereunto. I answer, that they were not all of one mind, for without doubt many of them were like unto Paul, unto whom that doth truly appertain, which he writeth elsewhere of the princes and rulers of this world, if they had known the wisdom of God they would never have crucified the Lord of glory; therefore, he speaketh not generally of all the rulers; but if any of them be curable, them doth he invite to repentance.

Footnotes

1 - "Perfidia," perfidy.

And now, brethren - Though they had been guilty of a crime so enormous, yet Peter shows the tenderness of his heart in addressing them still as his brethren. He regarded them as of the same nation with himself; as having the same hopes, and as being entitled to the same privileges. The expression also shows that he was not disposed to exalt himself as being by nature more holy than they. This verse is a remarkable instance of tenderness in appealing to sinners. It would have been easy to have reproached them for their enormous crimes; but that was not the way to reach the heart. He had indeed stated and proved their wickedness. The object now was to bring them to repentance for it; and this was to be done by tenderness, kindness, and love. People are melted to contrition, not by reproaches, but by love.
I wot - I know; am well apprised of it. I know you will affirm it, and I admit that it was so. Still the enormous deed has been done. It cannot be recalled, and it cam not be innocent. It remains, therefore, that you should repent of it, and seek for pardon.
That through ignorance - Peter does not mean to affirm that they were innocent in having put him to death, for he had just proved the contrary, and he immediately proceeds to exhort them to repentance. But he means to say that their offence was mitigated by the fact that they were ignorant that he was the Messiah. The same thing the Saviour himself affirmed when dying, Luke 23:34; "Father, forgive them, for they know not what they do." Compare Acts 13:27; 1-Corinthians 2:8. The same thing the apostle Paul affirmed in relation to himself, as one of the reasons why he obtained pardon from the enormous crime of persecution, 1-Timothy 1:13. In cases like these, though crime might be mitigated, yet it was not taken entirely away. They were guilty of demanding that a man should be put to death who was declared innocent; they were urged on with ungovernable fury; they did it from contempt and malice; and the crime of murder remained, though they were ignorant that he was the Messiah. It is plainly implied that if they had put him to death knowing that he was the Messiah, and as the Messiah, there would have been no forgiveness. Compare Hebrews 10:26-29. Ignorance, therefore, is a circumstance which must always be taken into view in an estimate of crime. It is at the same time true that they had opportunity to know that he was the Messiah, but the mere fact that they were ignorant of it was still a mitigating circumstance in the estimate of their crime. There can be no doubt that the mass of the people had no fixed belief that he was the Messiah.
As did also your rulers - Compare 1-Corinthians 2:8, where the apostle says that none of the princes of this world knew the wisdom of the gospel, for had they known it, they would not have crucified the Lord of glory. It is certain that the leading scribes and Pharisees were urged on by the most ungovernable fury and rage to put Jesus to death, even when they had abundant opportunity to know his true character. This was particularly the case with the high priest. But yet it was true that they did not believe that he was the Messiah. Their minds had been prejudiced. They had expected a prince and a conqueror. All their views of the Messiah were different from the character which Jesus manifested. And though they might have known that he was the Messiah; though he had given abundant proof of the fact, yet it is clear that they did not believe it. It is not credible that they would have put to death one whom they really believed to be the Christ. He was the hope, the only hope of their nation; and they would not have dared to imbrue their hands in the blood of him whom they really believed to be the illustrious personage so long promised and expected by their fathers. It was also probably true that no small part of the Sanhedrin was urged on by the zeal and fury of the chief priests. They had not courage to resist them; and yet they might not have entered heartily into this work of persecution and death. Compare John 7:50-53. The speech of Peter, however, is not intended to free them entirely from blame; nor should it be pressed to show that they were innocent. It is a mitigating circumstance thrown in to show them that there was still hope of mercy.

I wot - Οιδα, I know. Wot is from the Anglo-Saxon, to know; and hence wit, science or understanding.
Through ignorance ye did it - This is a very tender excuse for them; and one which seems to be necessary, in order to show them that their state was not utterly desperate; for if all that they did to Christ had been through absolute malice, (they well knowing who he was), if any sin could be supposed to be unpardonable, it must have been theirs. Peter, foreseeing that they might be tempted thus to think, and consequently to despair of salvation, tells them that their offense was extenuated by their ignorance of the person they had tormented and crucified. And one must suppose that, had they been fully convinced that this Jesus was the only Messiah, they never would have crucified him; but they did not permit themselves to receive conviction on the subject.

(3) And now, brethren, I wot that through ignorance ye did [it], as [did] also your rulers.
(3) It is best of all to receive Christ as soon as he is offered to us: but those who have neglected so great a benefit through man's weakness, yet have repentance as a means. As for the shame of the cross, we have to set against that the decree and purpose of God for Christ, foretold by the Prophets, how that first of all he would be crucified here upon the earth, and then he would appear from heaven the judge and restorer of all things, that all believers might be saved, and all unbelievers utterly perish.

And now, brethren,.... He calls them brethren, because they were so according to the flesh; and to testify his cordial love and affection for them.
I wot, or "I know",
that through ignorance ye did it; delivered up Jesus into the hands of Pilate; denied him to be the Messiah before him; preferred a murderer to him, and put him to death.
As did also your rulers; the members of the sanhedrim, some of them; see 1-Corinthians 2:8 for others of them knew him to be the Messiah, to be sent of God, by the miracles he did, and yet blasphemously ascribed them to Satan; and so sinning against light and knowledge, in such a malicious manner, sinned the sin against the Holy Ghost, to which ignorance is here opposed; and which did not excuse from sin: nor was it itself without sin; nor is it opposed to any sin, but to this now mentioned.

And now, brethren--Our preacher, like his Master, "will not break the bruised reed." His heaviest charges are prompted by love, which now hastens to assuage the wounds it was necessary to inflict.
I wot--"know."
through ignorance ye did it--(See marginal references, Luke 23:34; Acts 13:27; Acts 26:9).

I wot. I know. It was in ignorance of the majestic personality of Jesus that they slew him. Their rulers, ignorant also, might have known better had they not blinded themselves by prejudice. God "had foreshown all these things by the prophets," even that Christ should suffer. See Isaiah, chapter 53; Daniel 9:26.

And now, brethren - A word full of courtesy and compassion, I know - He speaks to their heart, that through ignorance ye did it - which lessened, though it could not take away, the guilt. As did also your rulers - The prejudice lying from the authority of the chief priests and elders, he here removes, but with great tenderness. He does not call them our, but your rulers. For as the Jewish dispensation ceased at the death of Christ, consequently so did the authority of its rulers.