Words and works are the main ways in which we act. Obviously much more goes on inside us, but words (spoken or written) and deeds (direct or indirect) are largely how we impact our world, to make a difference. Our impact can be for good (or not). This verse is about God helping us to be a force for good.
But first the converse, and why we need God’s help. Our natural tendencies are warped by sin, such that we incline towards ‘lustfulness… strife… rivalries… drunkenness… and things like these’(Galatians 5:19-21). In this letter to the Thessalonians the apostle Paul especially mentions walking ‘in rebellion’(2 Thessalonians 3:6&11) by which he means an undisciplined existence that’s lazy and a hindrance to others, rather than supportive and useful. These are surprisingly difficult negative drives to break, described by Paul elsewhere as ‘captivity under the law of sin which is in my members’(Romans 7:23) and by Jesus as ‘“The spirit indeed is willing, but the flesh is weak”’(Matthew 26:41). But God has better things for us, and can help us.
This is the key: we need God’s help; He can ‘establish’ us for good. Here Paul describes ‘our Lord Jesus Christ himself, and God our Father’(2 Thessalonians 2:16) drawing alongside us with ‘comfort’(2 Thessalonians 2:16&17) echoing ‘“the Counselor, the Holy Spirit”’(John 14:26), the guide who draws alongside (even within) to invigorate us. As Jesus put it, ‘“He who remains in me, and I in him,… bears much fruit,… apart from me you can do nothing”’(John 15:5). This is ‘the fruit of the Spirit’(Galatians 5:22), contrasting with the earlier list above, and includes ‘love, joy, peace, patience, kindness, goodness, faith(fullness), gentleness, and self-control’(Galatians 5:22-23). But these are more ways of being rather than specifics. What ‘works’ are we to pursue; what are we actually supposed to do?
This can include lots of things, and perhaps is well summarised by Paul’s prayer for the Thessalonians, that God would fulfil their ‘every desire of goodness and work of faith’(2 Thessalonians 1:11). The key is to be occupied by some useful activity that could be defined as good and flows from our faith. Paul emphasises to the Thessalonians the practical priority of earning an income for themselves, as responsible ‘good’ citizens. Flowing out from that comes having ‘something to give to him who has need’(Ephesians 4:28) – which is often best done indirectly through organisations, including Paul’s ‘contribution for the poor’(Romans 15:26) initiative. Others might provide direct practical help, like Tabitha who was ‘full of good works and acts of mercy’(Acts 9:36), which apparently involved making ‘coats and garments’(Acts 9:39) for those in need. In this way she indirectly ‘“‘clothed’”’(Matthew 25:36) Jesus himself, who in the same discourse recommended attending the sick and feeding the hungry etc. in a likewise manner.
Jesus did such things too, as He ‘“went about doing good”’(Acts 10:38), but He also ‘went about in all Galilee, teaching in their synagogues, preaching the Good News of the Kingdom’(Matthew 4:23). That brings us to the second part of Paul’s desire for the Thessalonians here, words. Obviously there is some overlap, since it’s possible to ‘labor in the word and in teaching’(1 Timothy 5:17), especially when such words require time and careful preparation, ‘whether by word [speech], or by letter’(2 Thessalonians 2:15). Clearly words include preaching and teaching, but also include the more informal being ‘ready to give an answer to everyone who asks you a reason concerning the hope that is in you’(1 Peter 3:15), and our general conversation being ‘seasoned with salt’(Colossians 4:6). Moreover, within the community of faith we should use words to encourage and ‘exhort one another day by day’(Hebrews 3:13), including of course ‘with psalms, hymns, and spiritual songs’(Colossians 3:16). Prayer usually involves words too.
Finally, there’s a balance to be had between works and words. To some extent this takes place within the body of Christ, the church, with some of us more works and some more word inclined, i.e. ‘service… teaching… exhorting: he who gives’(Romans 12:7-8) etc. However, as James warns us, each must seek their own balance too: ‘what good is it?’(James 2:16) to have words without practical works? This balance often evolves as life moves on and strength varies. There’s ‘a time to gather’(Ecclesiastes 3:5) knowledge/wisdom/skills/finance etc., and times to use them for good. Our store of such ‘“talents”’(Matthew 25:15) will change over time, as will our ability/opportunity to use them. Even Jesus spent well over a decade growing up, a similar length of time working as a ‘“carpenter”’(Mark 6:3), before a few years in full time ministry, then one final ‘“‘time’”’(John 12:27).