John Calvin on 2 Peter 3:4

4. Where is the promise. It was a dangerous scoff when they insinuated a doubt as to the last resurrection; for when that is taken away, there is no gospel any longer, the power of Christ is brought to nothing, the whole of religion is gone. Then Satan aims directly at the throat of the Church, when he destroys faith in the coming of Christ. For why did Christ die and rise again, except that he may some time gather to himself the redeemed from death, and give them eternal life? All religion is wholly subverted, except faith in the resurrection remains firm and immovable. Hence, on this point Satan assails us most fiercely.

But let us notice what the scoff was. They set the regular course of nature, such as it seems to have been from the beginning, in opposition to the promise of God, as though these things were contrary, or did not harmonize together. Though the faith of the fathers, they said, was the same, yet no change has taken place since their death, and it is known that many ages have passed away. Hence they concluded that what was said of the destruction of the world was a fable; because they conjectured, that as it had lasted so long, it would be perpetual.

2 Peter 3:5-8

5. For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water:

5. Nam hoe nesciunt volentes. quòd caeli jam olim fuerint, et terra ex aqua, et per aquam consistens, Dei sermone;

6. Whereby the world that then was, being overflowed with water, perished:

6. Per quae mundus qui tunc erat, aqua inundatus periit:

7. But the heavens and the earth, which are now, by the same word are kept in store, reserved unto fire against the day of judgment and perdition of ungodly men.

7. Qui autem nunc sunt coeli et terra, ejusdem sermone repositi sunt, et servantur igni in diem judicii et perditionis impiorum.

8. But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day.

8. Porri, ne hoc unum nos lateat, dilecti, quòd unus dies apud Dominum perinde est ut mille anni, et mille anni ut dies unus.