3:9 The Lord has not yet returned, says Peter, because He is patient with you, not wanting any to perish. "You" is variously interpreted as a reference to the letter's Christian recipients (identified in 1:1) or else more broadly as all people. In chapter 1 "you" and "your" both refer back to the recipients identified in 1:1 (see 1:2,4,5,8,10,11,12,13,15,16,19,20). Peter's later use of "dear friends," (3:1,8,14,17) seems also to point back to those identified in 1:1.
What Matthew Henry said about 2 Peter 3:9: [4]
That what men count slackness is truly long-suffering, and that to us-ward; it is giving more time to his own people, whom he has chosen before the foundation of the world, many of whom are not as yet converted; and those who are in a state of grace and favour with God are to advance in knowledge and holiness, and in the exercise of faith and patience, to abound in good works, doing and suffering what they are called to, that they may bring glory to God, and improve in a meetness for heaven; for God is not willing that any of these should perish, but that all of them should come to repentance. Here observe, 1. Repentance is absolutely necessary in order to salvation. Except we repent, we shall perish, Luke 13:3; Luke 13:5. 2. God has no delight in the death of sinners: as the punishment of sinners is a torment to his creatures, a merciful God does not take pleasure in it; and though the principal design of God in his long-suffering is the blessedness of those whom he has chosen to salvation, through sanctification of the spirit, and belief of the truth, yet his goodness and forbearance do in their own nature invite and call to repentance all those to whom they are exercised; and, if men continue impenitent when God gives them space to repent, he will deal more severely with them, though the great reason why he did not hasten his coming was because he had not accomplished the number of his elect. "Abuse not therefore the patience and long-suffering of God, by abandoning yourselves to a course of ungodliness; presume not to go on boldly in the way of sinners, nor to sit down securely in an unconverted impenitent state, as he who said (Matt. xxiv. 48), My Lord delayeth his coming, lest he come and surprise you;"
Here is what John Gill said: [5]
but is longsuffering to us-ward: not to all the individuals of human nature, for the persons intended by us are manifestly distinguished from "some men" in the text, and from scoffers, mocking at the promise of Christ's coming, in the context, 2Pe 3:3; and are expressly called beloved, 2Pe 3:1; and God's longsuffering towards them is their salvation, 2Pe 3:15, nor is it true of all men, that God is not willing that any of them should perish, and that everyone of them should come to repentance, since many of them do perish in their sins, and do not come to repentance, which would not be the case, if his determining will was otherwise; besides, a society or company of men are designed, to which the apostle himself belonged, and of which he was a part; and who are described, in his epistles, as the elect of God, called out of darkness, into marvellous light, and having obtained like precious faith with the apostles; and must be understood either of God's elect among the Jews, for Peter was a Jew, and they were Jews he wrote to; and then the sense is, that the delay of Christ's coming is not owing to any slackness in him, but to his longsuf...