Respectful customary greetings are in order when God’s people come together and/or communicate with each other. There is a dignity and respect we owe each other as those who are united in Christ Jesus. Whether it is the grace of God, or the peace that maintains the harmony between divergent people and personalities, God our Father and the Lord Jesus Christ are the Ones who bind us together.
The Holy Spirit is the Person in the Godhead who is the operational force behind a properly functioning assembly. The thankfulness that is a natural response when we hear of our brothers and sisters in Christ is motivated by the Spirit of God. The nearness of our thoughts to each other is promoted by the Spirit who leads us to intercede at the throne of grace for them. Thoughts of God’s people, and joy when we hear of their faith and testimony produces fellowship and gratitude as we think about the time we first knew each other. That fellowship in the Gospel includes remembering how God saved us. Then what I enjoy from day to day is because of constraining love when the Lord is the center of our lives. Paul would remember the constraint of the call of the Spirit to go to Macedonia. He no doubt thought about Lydia who quietly came into the kingdom of God without any fanfare. The young demon-possessed woman who was freed by the power of the name of Christ created a scene in the whole city. Satan doesn’t back off quietly. Paul would remember singing in the jail at the beginning of the work, the earthquake and the jailor being saved and his family. What fellowship! What joy! What confidence in God! Paul was thankful for them personally. He was also thankful for the fellowship in the Gospel: the life that he had in common with the believers; the love-constraining fellowship; the Lord Jesus who is central to fellowship.