Paul concludes the letter as he does all his letters, with some concluding advice. See 2-5 of chapter 4. He encourages them to "devote themselves to prayer . . . and pray for us (2-3)." The prayer he requests is specific -- that God will open a door for his preaching. (I would add pray for my mission team that leaves on Monday -- October 1 -- for Uganda for the same reasons). Paul adds that we should "conduct ourselves wisely toward those outside the church." Making the most of our time and opportunities.
In the final greetings section there are a few things to notice:
1. Notice that Mark, Barnabas' cousin, is with Paul (10). Mark had abandoned Paul and Barnabas on their first missionary journey and was the reason for Paul and Barnabas' falling out -- they formed new teams and went in separate directions. Barnabas wanted to give Mark another chance and Paul did not want to risk taking someone along who had abandoned them previously. I find it profoundly encouraging to see that Mark and Paul have reconciled and at this stage of the story they are working together.
2. Notice the reference to a letter to Laodicea (13). This letter has never been found.
3. Verse 14 -- another woman, Nympha, who has a church in her home. . .
Once again, Paul hand writes a greeting (18).