The word akatharsia means uncleanness, and the New Testament uses the word to refer to moral uncleanness. In Matt. 23:27, Jesus refers to the Pharisees who are whited sepulchres outside, but inside are full of all uncleanness. The pagan Gentiles had the same problem, and God gave them up to uncleanness (Rom. 1:24). The Roman Christians had previously given themselves up to uncleanness (Rom. 6: 19), but now they are charged to present their bodies to be slaves of righteousness and holiness. St. Paul was concerned that when he came to Corinth, he would find that a number of the believers there would not have repented of the “uncleanness and fornication and lasciviousness which they have committed” (2 Cor. 12:21). Paul also lists this state as one of the manifest works of the flesh (Gal. 5:19), and that those who are like this will not inherit the kingdom of God (v. 21). The Gentiles apart from Christ find themselves in this state naturally — “past feeling have given themselves over unto lasciviousness, to work all uncleanness with greediness” (Eph. 4:19). Christians should have nothing whatever to do with this state — “fornication, and all uncleanness, or covetousness, let it not be once named among you, as becometh saints” (Eph. 5:3). Christians nevertheless have to mortify this tendency within them, what Paul calls our “members which are upon the earth” (Col. 3:5). The company that this uncleanness keeps is entirely disreputable — fornication, inordinate affection, evil concupiscence, and covetousness, which is idolatry. Paul assures the Thessalonians that his appeals to them had not proceeded from uncleanness (1 Thess. 2:3). All Christians, whether in the ministry on in the congregation, are not called to uncleanness, but rather to holiness (1 Thess. 4:7).
The contextual sins surrounding this uncleanness are consistently the sins of wanting, desiring, lusting, grabbing, me-firsting, and envying. This means that selflessness and selfishness are not just oriented in different direction, like the arrow of a compass pointing north or south. Selflessness is clean and selfishness is consistently unclean. When we put ourselves in the central room of the house, we find it impossible to keep that room clean at all.