Lest Satan should get an advantage of us,.... Or make gain of us, or we should be circumvented by him; a metaphor taken from covetous persons, who take every occasion, and make use of every advantage to circumvent and deceive persons in trading with them: Satan gets an advantage of the churches, when church discipline is brought into neglect and contempt, or turned into tyranny; or when he can draw off any person from a church, or keep him out of it: wherefore the apostle's argument is, that since the incestuous person had true repentance for his sin, he ought to be forgiven, comforted, and received into the church; lest by too great severity, and a too long continuance of the censure on him, he should be either plunged into despair, or be drawn into a denial of the faith, or into an open scandalous course of wickedness; and so the church entirely lose a member, that might, by the proper use of discipline, have been an useful one, and Satan gain one:for we are not ignorant of his devices; and cunning stratagems; some of his crafty contrivances and designs are known, though not all of them; and this particularly, that he sometimes transforms himself into an angel of light, and under pretence of showing a just indignation against sin, and keeping up a strict and righteous discipline, destroys souls, ruins churches, and brings religion into contempt.
This was one of his devices in former times, that persons who fell into any gross sin after baptism, and a profession of religion, were never to be restored and received into the communion of the church again, let their repentance be ever so sincere.