John Calvin Commentary 2 Peter 1:8

"For if these things are yours and abound, they make you to be not idle nor unfruitful unto the knowledge of our Lord Jesus Christ." — 2 Peter 1:8 (ASV)

For if these things be in you. Then, he says, you will at last prove that Christ is really known by you, if you are endowed with virtue, temperance, and the other endowments. For the knowledge of Christ is an efficacious thing and a living root, which brings forth fruit. For by saying that these things would make them neither barren nor unfruitful, he shows that all those who boast of the knowledge of Christ without love, patience, and similar gifts, glory in vain and falsely that they have this knowledge, as Paul also says in Ephesians 4:20.

Ye have not so learned Christ, if so be that ye have heard him, and have been taught by him, as the truth is in Jesus, that ye put off the old man, etc.

For he means that those who possess Christ without newness of life, have never been rightly taught his doctrine.

But he would not have the faithful only be taught patience, godliness, temperance, and love; but he requires continual progress to be made in these endowments, and that justly, for we are still far from the goal. We ought, therefore, always to make progress, so that God’s gifts may continually increase in us.