These words are argumentative, and infer the indispensable duty of Christians to preserve themselves untainted from the idolatrous, impute world, by the consideration of the promises specified in the preceding chapter, I will dwell in you, and walk in you, and I will be your God, and ye shall be my people; a promise which contains the highest honour, and most perfect felicity, of the reasonable nature.
Now from hence he infers, That Christians having such promises, such helps and assistances, should cleanse themselves from sinful pollution, and endeavour after perfection in purity and holiness. Having therefore, &c.
Observe here, 1. The title wherewith the apostle addresses himself unto them, Dearly beloved; this expresses both the truth and also the strength of his affections towards them: By this appellation he recommends his counsel to their acceptance: For, as light opens the mind by clear conviction, so love opens the heart by persuasive insinuation.
Observe, 2. The matter of the address, and that is, to cleanse ourselves from all pollution both of spirit and flesh, and the changing of us into the unspotted image of God's holiness. The pollution of human nature is intimate and radical, diffused through all the faculties of the soul, and members of the body; we are therefore to pray for, and endeavour after renewing grace, and to be always advancing in holiness on earth, till we arrive at perfection in heaven.
Observe, 3. The motive exciting hereunto; namely, the exceeding great and precious promises assured to us from the mouth of God, Having these promises, let us cleanse ourselves.
Observe, 4. The means to help us therein, the fear of God. This grace has an eminent casuality and influence in a Christian's sanctification; it is a powerful restraint from sin both in thought and act, by considering that God's pure and flaming eyes see sin wherever it is, in order to judgment. An holy fear of God, and an humble fear of ourselves, will both restrain us from sin, and engages us to obedience.
From the whole, learn, That the promises of the gospel lay the most powerful obligations upon Christians to endeavour after, and strive for the attainment of pure and perfect holiness. As the pollution is universal, so must the cleansing be; and though thankful we must be for the least measure of sanctifying grace received, yet not satisfied with the greatest, short of our perfection; perfecting holiness in the fear of God.