Many of the Corinthian believers had been converted to Christ from paganism and idol worship. Clearly, much of the "worship" going on in pagan temples in Paul's day involved sacrifices, not to mute idols, but to demons (1 Cor 10:20). Paul pointed out to his converts a blatant contradiction:
"You cannot drink the cup of the Lord and the cup of demons too; you cannot have a part in both the Lord's table and the table of demons. Are we trying to arouse the Lord's jealousy? Are we stronger than he?" (vss.21,22).
Murray J. Harris has suggested the following:
"Paul is probably implying that the Corinthians had become defiled, perhaps by occasionally sharing meals at idol-shrines or by continuing to attend festivals or ceremonies in pagan temples (cf. 1 Cor. 8:10; 10:14-22), or even by maintaining their membership in some local pagan cult. If they made a clean break (cf. katharisomen, aorist [tense]) with pagan life in any and every form, they would be bringing their holiness nearer completion by this proof of their reverence for God" ("2 Corinthians" in Romans-Galatians, Vol.10 of 12, of * *. Gaebelein & Douglas, eds. Grand Rapids: Zondervan Publishing House, 1978, pp.360-361).
If some of the Corinthian believers were still "dabbling" in some aspects of a pagan lifestyle, Paul had the responsibility as their spiritual father to remind them of the dangers of slipping back into worldliness. Perhaps they were continuing to nurture their friendships with unbelievers in ways that tended to lead toward compromise their newfound faith in Jesus.
Not that the Corinthians had to separate themselves from the people in the world, but they did need to "keep their distance" from the immoral behavior of their pagan friends. As James put it, we need to keep ourselves
". . . unstained from the world" (1:27).
James uses the stained metaphor, and Paul uses the filthiness/defilement metaphor. Both apostles are saying Christians need to guard against being contaminated by the sin in the world. Interestingly, some of the healings Jesus performed on people in His day involved ridding people of demons, also called "unclean spirits" (according to the NASB in Mt 12:43; Mk 1:23; 3:30; 7:25; 9:17ff.; Lk 8:29; 9:42; 11:24; 13:11; the NIV refers to them as "evil spirits"). So now we have three similar words related to pollution or contamination of flesh and spirit: stains, filthiness, and uncleanness.
Furthermore, the unequal yoke Paul talked about in 6:14 was one such compromise in which some of the Corinthians were involved. This yoke could have involved forming business partnerships with unbelievers, which is applicable to Christians of all ages and cultures to this very day. The yoke could also be what is facetiously called a "missionary marriage" between a Christian and a non-Christian, in which the Christian, before the wedding, hopes to be a missionary to the non-Christian and lead him or her to Christ after they exchange wedding vows. This "plan" seldom goes as planned.
Paul goes to great lengths to explain that the value system of pagan culture and the value system of Christianity are like oil and water: they do not mix.
The word Paul uses as a contrast to filth and defilement is holiness. Evidently, Christians are capable of
"perfecting holiness in the fear of God" (7:1b).
Sanctification, or the process through which we as Christians become increasingly holy and Christ-like, is a lifelong process of transformation. Perfecting holiness is not "sinless perfection"; rather, it is a spiritual maturity that makes us "above reproach," as we increasingly become able through practice to distinguish good from evil (Heb 5:14).
In conclusion, while some of the Corinthians had to deal with sordid pasts involving demonic influence, sexual immorality, drunkenness, and other sins, as "new creations in Christ," these old things God had graciously forgiven. He had wiped the slate clean, and the Corinthians were now to be characterized by a new way of life, free from the domination of habitual sin.
In our post-modern world, we may find it difficult to identify with the notion of idolatry, as it was practiced in Paul's day. We are safe to assume, however, that while we may not bow down to idols of wood and stone and metal, we do have our post-modern idols, which are too numerous to mention. The challenge for us today, as it was in Paul's day, is to keep our flesh and spirit going and growing in the direction of holiness, with a healthy fear of and reverence for the Lord, who Himself is holiness personified.