Matthew Henry Commentary 2 Peter 3:5-10

"For this they willfully forget, that there were heavens from of old, and an earth compacted out of water and amidst water, by the word of God; by which means the world that then was, being overflowed with water, perished: but the heavens that now are, and the earth, by the same word have been stored up for fire, being reserved against the day of judgment and destruction of ungodly men. But forget not this one thing, beloved, that one day is with the Lord as a thousand years, and a thousand years as one day. The Lord is not slack concerning his promise, as some count slackness; but is longsuffering to you-ward, not wishing that any should perish, but that all should come to repentance. But the day of the Lord will come as a thief; in the which the heavens shall pass away with a great noise, and the elements shall be dissolved with fervent heat, and the earth and the works that are therein shall be burned up." — 2 Peter 3:5-10 (ASV)

If these scoffers had considered the dreadful vengeance with which God swept away a whole world of ungodly men at once, surely they would not have scoffed at His threatening an equally terrible judgment. The heavens and the earth that now exist, by the same word, it is declared, will be destroyed by fire. This is as sure to come as the truth and the power of God can make it.

Christians are here taught and established in the truth of the coming of the Lord. Though, in human reckoning, there is a vast difference between one day and a thousand years, yet, in God's reckoning, there is no difference. All things past, present, and future are always before Him: the delay of a thousand years cannot mean as much to Him as putting off anything for a day or an hour means to us.

If people have no knowledge or belief of the eternal God, they will be very likely to think of Him as being like themselves. How hard it is to form any thoughts of eternity! What people consider slowness is long-suffering, and that toward us; it is giving more time to His own people 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.

Therefore, settle it in your hearts that you will certainly be called to give an account of all things done in the body, whether good or evil. And let a humble and diligent walking before God, and a frequent judging of yourselves, show a firm belief in the future judgment, though many live as if they were never to give any account at all. This day will come when people are secure and have no expectation of the Day of the Lord.

The stately palaces, and all the desirable things in which worldly-minded people seek and place their happiness, will be burned up; all kinds of creatures God has made, and all human works, must pass through the fire, which will be a consuming fire to all that sin has brought into the world, though a refining fire to the works of God's hand. What will become of us if we set our affections on this earth and make it our portion, since all these things will be burned up?

Therefore, secure happiness beyond this visible world.