John Gill emphasizes the necessity of possessing and practicing spiritual qualities as outlined in 2 Peter 1:8. He explains that true knowledge of Christ is not merely theoretical but must be accompanied by practical application and the fruits of righteousness in one's life. Gill warns against a barren and unfruitful faith that lacks genuine experience and trust in Christ, contrasting it with a vibrant faith that flourishes like a well-watered tree. He encourages believers to actively cultivate these graces to ensure they are fruitful in their knowledge of the Lord. Ultimately, the sermon calls for a deep, experiential relationship with Christ that manifests in a life of obedience and good works.

Ver. 8. For if these things be in you,.... Are wrought in you by the Spirit of God, and exercised and performed by his assistance, who works in his people both to will and do: and abound; increase in their acts and exercises by the frequent performance of them: they make you; both by way of influence and evidence, [that ye shall] neither [be] barren nor unfruitful in the knowledge of our Lord Jesus Christ. There is a knowledge of Christ which is barren and fruitless; and those that have it are so in their conversations, and it will be of no avail to them another day: and this is a mere notional and speculative knowledge, such as is not attended with any inward experience and application of Christ to themselves, or any fruits of righteousness in their lives, and is a bare theory of things relating to his person, offices, and works; but there is a knowledge of him that is spiritual and experimental, by which a soul not only approves of Christ, but places its trust and confidence in him, and appropriates him to himself, and practically observes his commands and ordinances in the faith of him; and in love to him he performs the above duties, and exercises the above graces; from whence it appears, that he is neither barren nor unfruitful himself in the profession of his knowledge of Christ; "or in the acknowledgment of him", as it may be rendered; nor is that a vain, empty, and useless thing: he is not like the barren fig tree, or the earth that bears briers and thorns, and is nigh to cursing and burning, but like a tree planted by a river of water, and is green, flourishing, and fruitful. This is used as an argument to enforce the foregoing exhortation, to add to, that is, to exercise and perform the above graces and duties, in conjunction with each other.