‘Finally then, brothers and sisters, we beseech and exhort you in the Lord Jesus, that as you received of us how you ought to walk and to please God, even as you do walk - that you abound more and more.'
‘Finally.' The word is regularly used by Paul in this sense having the idea of ‘for the remainder' (loipos means ‘the rest, the remainder'). But it is not necessarily an indication of finality, having also the meaning ‘furthermore, moreover'. Here it signifies an addition to, and connection with, what has gone before without necessarily indicating that the letter is nearly over.
‘We beseech and exhort.' We may paraphrase ‘request and urge you strongly, calling upon you to --'. The first verb is to soften up the second verb, making it more friendly.
‘In the Lord Jesus.' Both are ‘in Christ', and his urgings relate to this fact. Being His what he speaks about is required of both him and them because they are His.
‘Lord Jesus' (1 Thessalonians 2:15; 1Th 2:19; 1 Thessalonians 3:11; 1 Thessalonians 3:13; 1 Thessalonians 4:1-2) and ‘the Lord' (1Th 1:6; 1 Thessalonians 3:8; 1 Thessalonians 3:12; 1Th 4:6; 1 Thessalonians 4:15 (twice), 1 Thessalonians 4:16; 1 Thessalonians 4:17 (twice); 1 Thessalonians 5:2; 1 Thessalonians 5:12; 1 Thessalonians 5:27) are Paul's regular descriptions of Christ in the central part of this letter, although he opened with reference to ‘the Lord Jesus Christ' (1 Thessalonians 1:1; 1 Thessalonians 1:3) and closes similarly (1 Thessalonians 5:9; 1 Thessalonians 5:23; 1 Thessalonians 5:28). He also uses ‘Jesus' (1Th 1:10; 1 Thessalonians 4:14 (twice)) and ‘in Christ Jesus' (1 Thessalonians 2:14; 1 Thessalonians 5:18). ‘Christ' appears alone as a genitive (1 Thessalonians 2:6; 1 Thessalonians 3:2) and once as ‘in Christ'.
It seems probable that we can see ‘Lord Jesus' and ‘Lord' as simply abbreviations and variations of the full ‘Lord Jesus Christ' (which he uses comparatively more often in the second letter), with the grander phrase being used to open and close, especially as ‘Lord Jesus' is also used in parallel with God the Father (1 Thessalonians 3:11). ‘Jesus' is twice used in connection with His death and resurrection (1 Thessalonians 1:10; 1 Thessalonians 4:14 a), stressing His manward side, although the third use (1 Thessalonians 4:14 b) connects more with the other uses, probably affected by the previous use in the verse. ‘In Christ Jesus' and ‘in Christ' are again simply variations (although ‘the dead in Christ' may have become a technical term) for he can also say ‘in the Lord Jesus Christ' (1 Thessalonians 1:1; 1 Thessalonians 1:3), ‘in the Lord' (1 Thessalonians 3:8; 1 Thessalonians 5:12) and ‘in the Lord Jesus' (1 Thessalonians 4:1).
‘That as you received of us how you ought to walk and to please God, even as you do walk - that you abound more and more.' This was what he exhorts them to do. Firstly he stresses that they had learned from him and his companions, both by example and teaching, how they should walk and thus please God, then he assures them that he does know that they are walking like this, and finally he stresses the need to abound more and more. He goes out of his way to be tactful and not cause offence, while achieving his object in stressing the need to continue to grow. It reminds us that Paul only behaved like a sergeant major when it was necessary.
‘You ought to walk.' The phrase is strong, ‘how it is necessary for you to walk'. It was not a matter of choice or opinion. ‘Walking' was a verb regularly used of living life in a certain way. It stressed the need for continual right behaviour and attitude, step by step, hour by hour, through life.
‘Abound more and more.' In 1 Thessalonians 3:12 he spoke of ‘abounding in love', now it expands to abounding more and more in everything good, although those who genuinely do the one will do the other (compare 1 Thessalonians 3:10). And he wants them to realise that they will never achieve the goal in this life, rather they are to be, and will be, changed from glory into glory as they become more like Him (2 Corinthians 3:18), ever growing, ever becoming more Christ-like.
This is especially true in that he connects this with an indictment of sexual misbehaviour (verses 3-8). Many men of God have a continual battle with their natural sexual proclivities which they have to fight at various times all their lives until death brings release, something which others know little about and therefore have little sympathy with. For the former it will be a battle to the end, even though victory is continually obtained. Becoming a Christian does not remove the cravings of the flesh, it gives strength to overcome them for those who walk wisely and prayerfully and avoid causes of temptation (2 Timothy 2:21-22).