From those turn away. This exhortation sufficiently shows that Paul does not speak of a distant posterity, nor foretell what would happen many ages afterwards; but that, by pointing out present evils, he applies to his own age what he had said about "the last times;" for how could Timothy "turn away" from those who were not to arise till many centuries afterwards? So then, from the very beginning of the gospel, the Church must have begun to be affected by such corruptions.

Having a form of godliness - That is, they profess religion, or are in connection with the church. This shows that the apostle referred to some great corruption in the church; and there can be little doubt that he had his eye on the same great apostasy to which he refers in 2 Thes. 2:, and 1 Tim. 4: All these things to which he refers here have been practiced and tolerated in that apostate church, while no body of men, at any time, have been more zealous in maintaining "a form of godliness;" that is, in keeping up the forms of religion.
But denying the power thereof - Opposing the real power of religion; not allowing it to exert any influence in their lives. It imposes no restraint on their passions and carnal propensities, but in all respects, except in the form of religion, they live as if they had None. This has been common in the world. The most regular and bigoted adherence to the forms of religion furnishes no evidence in itself that there is any true piety at heart, or that true religion has any actual control over the soul. It is much easier for people to observe the forms of religion than it is to bring the heart under its controlling influence.
From such turn away - Have no contact with them as if they were Christians; show no countenance to their religion; do not associate with them; compare 2-John 1:10-11; see the notes at 2-Corinthians 6:17.

Having a form of godliness - The original word μορφωσις signifies a draught, sketch, or summary, and will apply well to those who have all their religion in their creed, confession of faith, catechism, bodies of divinity, etc., while destitute of the life of God in their souls; and are not only destitute of this life, but deny that such life or power is here to be experienced or known. They have religion in their creed, but none in their hearts. And perhaps to their summary they add a decent round of religious observances. From such turn away - not only do not imitate them, but have no kind of fellowship with them; they are a dangerous people, and but seldom suspected, because their outside is fair.

Having a form of godliness, but denying the power thereof: (2) from such turn away.
(2) We must not tarry with those men who resist the truth not from simple ignorance, but from a perverse mind, (which thing appears by their fruits which he graphically displays here); rather, we must turn away from them.

Having a form of godliness,.... Either a mere external show of religion, pretending great piety and holiness, being outwardly righteous before men, having the mask and visor of godliness; or else a plan of doctrine, a form of sound words, a scheme of truths, which men may have without partaking of the grace of God; and which, with respect to the doctrine of the Trinity, the church of Rome has; or else the Scriptures of truth, which the members of that church have, and profess to hold to, maintain and preserve; and which contains doctrines according to godliness, and tend to a godly life and godly edification:
but denying the power thereof; though in words they profess religion and godliness, the fear of God, and the pure worship of him, yet in works they deny all; and though they may have a set of notions in their heads, yet they feel nothing of the power of them on their hearts; and are strangers to experimental religion, and powerful godliness: or though they profess the Scriptures to be the word of God, yet they deny the use, the power, and efficacy of them; they deny the use of them to the laity, and affirm that they are not a sufficient rule of faith and practice, without their unwritten traditions; and that they are not able to make men wise, or give them a true knowledge of what is to be believed and done, without them; and that the sense of them is not to be understood by private men, but depends upon the infallible judgment of the church or pope:
from such turn away; have no fellowship with them, depart from their communion, withdraw from them, and come out from among them: this passage sufficiently justifies the reformed churches in their separation from the church of Rome.

form--outward semblance.
godliness--piety.
denying--rather as Greek, "having denied," that is, renounced.
the power--the living, regenerating, sanctifying influence of it.
turn away--implying that some of such characters, forerunners of the last days, were already in the Church.

Having a form - An appearance of godliness, but not regarding, nay, even denying and blaspheming, the inward power and reality of it. Is not this eminently fulfilled at this day?