‘For this is the will of God, even your sanctification, that you abstain from fornication, that each of you know how to possess himself of his own vessel in sanctification and honour, not in the passion of lust like the Gentiles who do not know God. That no man transgress and wrong his brother in the matter, because the Lord is an avenger in all these things, as also we forewarned you and testified. For God called us not to uncleanness but in sanctification.'
The passage must be read as one whole, for each part defines the other. It is dealing with the major moral problem that faced Christians in the first century, and faces them in many countries today, of lax and loose sexual behaviour. Marriage for some had become a mockery. Many religions in the first century encouraged sexual misbehaviour and laxity. Sacred prostitutes were common, with whom sex was seen as a form of worship, and ‘love feasts' (see 2 Peter 2:13-14), orgies, where anything went and was even looked on as religious activity, were a favourite pastime for many. Indeed the practise later invaded the Christian church causing major condemnation from Christ (Revelation 2:6; Revelation 2:14-15; Revelation 2:20-23). This was especially prevalent in the area of the world in which the Thessalonians lived. Thus becoming Christians had faced them with a totally new way of life.
‘This is the will of God, even your sanctification.' The will of God for His people determines, among other things (‘will' has no article), that they should be separated to Him and therefore holy. And here we learn that this especially applies to the avoidance of wrong sexual practises. Here sanctification is the process of being made truly holy and Christ-like.
Now Paul delineates three things that the Christian must avoid, ‘that you abstain from fornication -- that each one of you know how to possess himself -- that no man transgress and wrong his brother.'
‘That you abstain from fornication.' Fornication is a general word signifying sex engaged in outside a formal marriage relationship, and includes sex engaged in with other than one's first wife while she is still alive, unless she herself has first committed fornication (and vice versa), and any forms of perverted sex. ‘From', included in the verb, is emphasised by the further use of a preposition. They are to keep far from such things.
‘That each of you know how to possess himself of his own vessel in sanctification and honour, not in the passion of lust like the Gentiles who do not know God.' ‘The Gentiles' in general were ruled by their lustful passions. But that was the opposite of how Christians should behave. They should be ruled by spiritual ideals under God. Thus they are like the holy vessels set apart on the Tabernacle and must rule their bodies as ‘holy vessels' set apart for God, dedicated to God's service. They must do all as in the sight and presence of God. Their whole manner of life will be different, for their primary aim and responsibility will be to please and to serve God. See 2 Timothy 2:20-22 for a similar comparison of a man with a vessel (skeuos) unto honour, which must avoid ‘youthful lusts', a good parallel to here. See also 2 Corinthians 4:7 for men as ‘earthen vessels'.
‘The passion of lust.' Something which possesses the mind as an overriding feature and results in outward lust, making someone surrender to their passion. This was especially prevalent in a world where there were few barriers.
It should be noted that this is not saying that all Gentiles behaved openly in this way, just as not all openly live immorally today, although society in those days did not generally frown so much on such behaviour. It is rather indicating the passions that controlled the majority of them and which they followed when they could, and which many of their religions and societies encouraged them to practise openly. Similarly, many a ‘respectable' man or woman today goes on the internet and indulges in sexual appetites in secret, hidden behind anonymity, and enjoys on television the corruptness of society. But their behaviour is known to God (and recorded secretly on their computer). What we laugh or gaze at in secret indicates what we are. For an honest and open indictment of Gentile belief and behaviour see Romans 1:18-32.
The verb translated ‘possess' has mainly the meaning of ‘acquire', but then went on to mean that having acquired you possessed. We might translate ‘gain and keep control over'. Control is the central idea. ‘Know to' may indicate knowing that they are responsible to, rather than simply knowing how to (there is no specific ‘how' in the Greek or in the verb).
So each is responsible for his own ‘vessel'. To control it and keep it as holy to God and honourable, ‘a vessel unto honour' (2 Timothy 2:21), or to prostitute it and make it dishonourable, ‘unto dishonour'.
Some see the ‘vessel' as indicating the wife. Wives are elsewhere called ‘the weaker vessel' (1 Peter 3:7). But that then also makes the husband a vessel also, ‘the stronger vessel'. There is not there the suggestion, as there would be here, that the man possesses the wife like a chattel. The latter was not the Christian view (Galatians 3:28; Ephesians 5:28). It is true that the verb can also be used of acquiring a wife. But there is nothing obvious in the context to support the idea here and it is a good principle in interpreting Scripture to take the obvious interpretation where two interpretations clash. If Paul meant a wife why did he not say so? Nor does it fit well with 1 Thessalonians 4:6.
‘Who do not know God.' For if they did they would be aware that their sexual behaviour was contrary to His nature. Romans 1:18-32 links the sins of the Gentiles with the fact that they do not know God because they close their eyes to His appeal through nature and conscience and turn to idolatry. Thus they worship beasts and behave like them.
‘That no man transgress and wrong his brother in the matter, because the Lord is an avenger in all these things, as also we forewarned you and testified.' Sexual sin not only affects us, it affects others. It defrauds and takes advantage of others. It destroys marriages, breaks up relationships, makes a mockery of genuine love, drags men and women down to a lower level of living, and dishonours God (1 Corinthians 6:15-16; 1 Corinthians 6:18-19). And when we so lead others astray or hurt them, the Lord will avenge them, either at the day of judgment, or by illness and disease (1 Corinthians 11:30).
There is no reason for considering that ‘brother' here means any different from elsewhere. It refers to a fellow-Christian. Sexual transgression in the church was most likely to affect other Christians, especially in days when free time was limited, and that would be a great sin for it would be a sin against a brother which the Lord will avenge. And even sex outside the church community would harm fellow-Chrisitian for it would bring shame on the church and on each brother.
‘For God called us not to uncleanness but in sanctification.' Paul finally summarises the position. Sexual purity is part of the call of God. There are two options, being involved in uncleanness or being in sanctification. God's call is from the one to the other. If we are those who are called by God then we do not have an option, for our behaviour and attitude will reveal the genuineness of our calling. Again this sanctification is to be practical and not imputed, although resulting from having been first sanctified by God (1Co 1:2; 2 Thessalonians 2:13; 1 Peter 1:2).