‘And we exhort you, brothers and sisters, admonish the disorderly, encourage the fainthearted, support the weak, be longsuffering towards all. See that none render to anyone evil for evil, but always follow after that which is good.'
‘Brothers and sisters'. The work of the leaders, as described here, is to be supported and entered into by all on behalf of the whole church. The ‘disorderly' or ‘lazy' are to be admonished. The word for disorderly originally referred to soldiers who broke ranks, and then to anything out of order. Thus any displays of lack of unity are to be sorted out, and if necessary dealt with. Some, however, see the word as referring, as it can, to the culpably lazy. Paul may well have had in mind those who had ceased work because ‘Christ was coming' (1 Thessalonians 4:11-12; 2 Thessalonians 3:11). But it also refers to those who are disorderly in doctrine (2 Thessalonians 3:6). The fainthearted must be encouraged, or comforted in order to give them more strength. The spiritually weak would include those still babes in Christ (1 Corinthians 3:1-2; 1 Peter 2:2), but would also include some who by their very nature always continue to need help, who are to be supported and nurtured. Compare Romans 14:1-8; Romans 14:13-23; 1 Corinthians 8:1-13. Longsuffering and patience is to be shown to all. This is the way the church should be (1 Corinthians 13:4-8).
Note the threefold injunctions, ‘admonish -- encourage -- support' which are then held together by the fourth.
‘See that none render to anyone evil for evil, but always follow after that which is good.' For this we can compare Matthew 5:38-48. The Christian is above mere retaliation and revenge. Those can be left in the hands of God (compare Romans 12:17-21; 1 Peter 3:9-12). Rather he must seek to follow the good for the benefit of all. This is especially to be true between fellow-Christians.
‘Always follow after that which is good.' The verb is fairly strong, ‘pursue, run after'. The Christian is to pursue what is good.