'Union' in the Bible

From: Paul, Silvanus, and Timothy. To: The church of the Thessalonians in union with God the Father and the Lord Jesus, the Messiah. May grace and peace from God our Father and the Lord Jesus, the Messiah, be yours!

For you, brothers, became imitators of the churches of God in Judea that are in union with the Messiah Jesus. You suffered the same persecutions from the people of your own country as they did from those Jews

Finally, believers, we ask and admonish you in the Lord Jesus, that you follow the instruction that you received from us about how you ought to walk and please God (just as you are actually doing) and that you excel even more and more [pursuing a life of purpose and living in a way that expresses gratitude to God for your salvation].