'Put to death, therefore, whatever belongs to your earthly nature: sexual immorality, impurity, lust, evil desires and greed, which is idolatry. '
Colossians 3:5 https://www.bible.com/bible/113/COL.3.5 NIVUK
Biblical Hermeneutics Stack Exchange is a question and answer site for professors, theologians, and those interested in exegetical analysis of biblical texts. It only takes a minute to sign up.Sign up to join this community
Akatharsia in the context of Paul's Epistles refers to sexual impurity, and not heresy.
Heresy - αἵρεσις
"Heresy" (αἵρεσις - airesis) in the New Testament simply means "sect" or "faction". Christianity was considered an airesis by the Jews (Acts 24:14). Paul will himself write of Christian heresies in other of his letters. The KJV translates
1 Corinithians 11:19 (KJV)
For there must be also heresies among you, that they which are approved may be made manifest among you.
Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies
Peter also writes against heresy (2:1):
But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction.
ἀκαθαρσία (akatharsia) is a different word meaning essentially impurity. The related adjective ἀκάθαρτος (akatharos) is the opposite (signified by the prefix "a-") of καθαρός (katharos), meaning pure, clean, or spotless.
Akatharsia is the word used in the Greek Septuagint to refer to the ritual uncleanness discussed in the Levitical rules (e.g. 5:3, 7:20-21, 15:3). But it also can refer to impurity in the non-Levitical sense as well; for example:
Proverbs 6:16 LXX
ὅτι χαίρει πᾶσιν, οἷς μισεῖ ὁ κύριος, συντρίβεται δὲ διʼ ἀκαθαρσίαν ψυχῆς,
For he rejoices in all things which God hates, and is ruined by reason of impurity of soul (Brenton tr.)
The word appears 10 times in the New Testament - once in Matthew and the other 9 times in Paul's Epistles. Paul seems to almost always associate akatharsia with sexual impurity. The word is always translated as "uncleanness" in the KJV; other versions alternate between "impurity" and "uncleanness". Examples:
Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves
Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness
2 Corinthians 12:21
And lest, when I come again, my God will humble me among you, and that I shall bewail many which have sinned already, and have not repented of the uncleanness and fornication and lasciviousness which they have committed.
At this stage there is a bit to early to talk about heresy. Paul borrows "akatharsia" from the hellenistic Judaism as meaning "alienation from God", disregarding the ritual significance of the word ("impurity, uncleanness" as in Leviticus). There is a transition to a rather moral and spiritual outlook. And NO, Paul does NOT always associate "akatharsia" with sexual impurity. Sometimes it does, indeed.
This view that the sexual makes cultically unclean is expressed in, say, Leviticus 20:21, as "akatharsia".
Leviticus 20:21 'If a man marries his brother's wife, it is an act of impurity; he has dishonored his brother. They will be childless. (NIV)
However, in the OT, "akatharsia" is also used for expressing things connected with idolatrous cults:
Ezekiel 36:17 Son of man, when the people of Israel were living in their own land, they defiled it by their conduct and their actions. Their conduct was like a woman's monthly uncleanness in my sight. (NIV)
It is the task of the priest to distinguish between clean and unclean, Lv. 10:10; Ez. 22:26, and to prescribe the rites to restore persons or things to the cleanness which they have lost.
Leviticus 10:10 ... so that you can distinguish between the holy and the common, between the unclean and the clean (NIV)
Leviticus 16:16 In this way he will make atonement for the Most Holy Place because of the uncleanness and rebellion of the Israelites, whatever their sins have been. He is to do the same for the tent of meeting, which is among them in the midst of their uncleanness. (NIV)
In particular, anything associated with a foreign cult, or hostile to Yahweh, is unclean. In Leviticus it seems that the ritual and the moral are rather intertwined. In worship and ritual, the concept of ritual purity is strong. Whereas in the prophetic discourse "akatharsia" is used as to mainly express the religious and moral inadequacy of a sinner with respect to God. The prophets will develop an ethical side of the matter. For them, ethical purity is so important and "akatharsia" (ethical impurity) is so defiling, as it prevents man to get in touch with the Lord:
Isaiah 1:15-16 So when you spread out your hands in prayer, I will hide My eyes from you; Yes, even though you multiply prayers, I will not listen. Your hands are covered with blood. Wash yourselves, make yourselves clean; Remove the evil of your deeds from My sight. Cease to do evil,… (NASB)
Here, "hands covered with blood" = unclean, impure (not necessarily out of sexual reasons)
Isaiah 6:5 Woe to me!" I cried. "I am ruined! For I am a man of unclean lips, and I live among a people of unclean lips, and my eyes have seen the King, the Lord Almighty. (NIV)
Psalm 51:2 Wash away all my iniquity and cleanse me from my sin. (NIV)
Jeremiah 33:8 I will cleanse them from all the sin they have committed against me and will forgive all their sins of rebellion against me. (NIV)
In wisdom literature as well:
Proverbs 6:16 There are six things which the Lord hates, Yes, seven which are an abomination to Him (NASB)
Likewise in Proverbs 3:32; 16:5, "akatharsia" for תּוֹעֵבָה (abomination).
It is obviously a spiritualized concept of purity-impurity ("akatharsia") and a more general one. Perhaps we could generalize by saying that "akatharsia" is that what the Lord hates.
Now what Paul is doing out of all these? It might be that the use of the word in Greek legal discourse have had some influence here. For instance:
Demosthenes, Against Midias, 21.119; ... τοῦτο γάρ, τοῦτ᾽ οὐκἔχον ἐστὶν ὑπερβολὴν ἀκαθαρσίας [uncleanness, foulness, vileness] ... for vileness is impossible to beat (A. T. Murray, 1939)
Plato, Leg., IX, 854b ... ἐκ παλαιῶν καὶ ἀκαθάρτων τοῖς ἀνθρώποις ἀδικημάτων ... from ancient wrongs ... unexpiated (R.G. Bury, 1968)
Plato, Leg., IX, 854b: δοῦλον δ᾽ ὁ κτείνας ἑαυτοῦ μὲν καθηράσθω, ἐὰν δὲἀλλότριον θυμῷ, διπλῇ τὸ βλάβος ἐκτεισάτω τῷ κεκτημένῳ. ὅστις δ᾽ ἂν τῶνἀποκτεινάντων πάντων μὴ πείθηται τῷ νόμῳ, ἀλλ᾽ ἀκάθαρτος ὢν ἀγοράν τεκαὶ ἆθλα καὶ τὰ ... He that slays a slave of his own shall purify himself; and if he kill another man's slave in rage, he shall pay to the owner twice the damage. And if anyone of all these types of slayers disobeys the law and, being unpurified, defiles the market and the games and other sacred assemblies, whoso pleases shall prosecute (R.G. Bury, 1968)
It is mostly about moral issues, about discipline and personal behavior.
And in the NT writings, "akatharsia" has a broader meaning.
almost like in the OT Law:
Matthew 23:27 Woe to you, teachers of the law and Pharisees, you hypocrites! You are like whitewashed tombs, which look beautiful on the outside but on the inside are full of the bones of the dead and everything unclean. (NIV) Also in Luke 11:41.
not like in the OT Law:
Acts 10:28 He said to them: "You are well aware that it is against our law for a Jew to associate with or visit a Gentile. But God has shown me that I should not call anyone impure or unclean. (NIV)
Galatians 2:11-12 When Cephas came to Antioch, however, I opposed him to his face, because he stood to be condemned. For before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself, for fear of those in the circumcision group. (NASB)
The Christian community don't engage in ritual purification after dealings with non Jewish poeple. The purity of the community consists in full and unreserved self-offering to God. Spiritual impurity (intellectual, moral, physical) excludes man from fellowship with God.
In Paul we can find more clearly this transition from the OT cultic view of uncleanness (ἀκαθάρτουμὴ ἅπτεσθε) to the NT moral and spiritual view, as undertaking and continuing the OT prophetic outlook. For Paul, "akatharsia" denotes sometimes the immoral state of the pre-Christian life:
1 Thessalonians 4:7 For God did not call us to be impure, but to live a holy life. (NIV)
Paul is taking a very liberal attitude towards the cultic meaning of "akatharsia" ...
Romans 14:20 All food is clean, but it is wrong for a person to eat anything that causes someone else to stumble. (NIV)
... and is undertaking the OT prophetic outlook:
2 Corinthians 7:1 Therefore, since we have these promises, dear friends, let us purify ourselves from everything that contaminates body and spirit, perfecting holiness out of reverence for God. (NIV)
Galatians 5:19 The acts of the flesh are obvious: sexual immorality, impurity and debauchery (NIV)
As we can see, in Paul's writings ἀκαθαρσία = ἔργον τῆς σαρκός, impurity is an act of the flesh, it is an expression of the nature of the unregenerate man whose action is determined by commitment, not to God, but to his natural instincts.