Albert Barnes Commentary 2 Peter 3:18

"But grow in the grace and knowledge of our Lord and Saviour Jesus Christ. To him [be] the glory both now and for ever. Amen." — 2 Peter 3:18 (ASV)

But grow in grace. . Religion in general is often represented as grace, since every part of it is the result of grace, or of unmerited favor; and to “grow in grace” is to increase in that which constitutes true religion. Religion is as susceptible to cultivation and growth as any other virtue of the soul.

It is feeble in its beginnings, like the grain of mustard seed, or like the germ or blade of a plant, and it increases as it is cultivated. There is no piety in the world that is not the result of cultivation, and that cannot be measured by the degree of care and attention bestowed upon it.

No one becomes eminently pious, any more than one becomes eminently learned or rich, who does not intend to; and ordinarily, people in religion are what they design to be. They have about as much religion as they wish and possess about the character that they intend to possess. When people reach extraordinary elevations in religion, like Baxter, Payson, and Edwards, they have gained only what they meant to gain. The showy and worldly professors of religion, who have little comfort and peace, have in fact the characters that they designed to have. If these things are so, then we may see the propriety of the injunction “to grow in grace;” and then too we may see the reason why such feeble attainments are made in piety by the great mass of those who profess religion.

And in the knowledge of our Lord and Saviour Jesus Christ. .

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To know the Lord Jesus Christ—to possess just views of His person, character, and work—is the sum and essence of the Christian religion. With this injunction, therefore, the apostle appropriately closes this epistle.

One who has a saving knowledge of Christ has, in fact, all that is essential for his welfare in the present life and in the life to come. One who does not have this knowledge, though he may be distinguished in academic learning and profoundly skilled in the sciences, has in reality no knowledge that will benefit him in the great matters pertaining to his eternal welfare.

To Him be glory, etc. (2 Timothy 4:18).

With the desire that honor and glory should be given to the Redeemer, all the aspirations of true Christians appropriately close. There is no wish more deeply cherished in their hearts than this; there is nothing that will enter more into their worship in heaven. (Revelation 5:12–13).