To be in Christ, signifieth:
1. Their being Christians indeed; they having received Christ by a true and lively faith, and given themselves to the obedience of his precepts. In this sense the apostle saith: If any man be in Christ he is a new creature.
2. Their being Christians in name, by baptism and outward profession. These churches are said to be in Christ in this latter sense. We have a parallel text, 1 Thessalonians 2:14. They do not judge improperly, who think that by Judea here is not meant the province, but the whole country of Judea; which comprehended not Judea only, but Samaria and Galilee. John Baptist and our Saviour (who both mostly preached in Galilee) had prepared their due matter for gospel churches. Peter, and John, and Philip, preached the gospel in many villages of the Samaritans, Acts 8:25,40. Of all these churches Paul speaks, telling us he was personally unknown unto them; so far he was from learning the Christian doctrine from the apostles or them.