Depending on your translation, Colossians 3:1 begins with a “Since, then,” an “If then,” or a “Therefore.” The point being that what Paul is about to say builds on something he has previously said. We don’t have to wonder what that antecedent is because Paul tells us—it’s the fact that we’ve been “raised with Christ” (3:1).
This takes us back to his discussion of how the disciples at Colossae were made “alive with Christ” and forgiven of all their sins (v. 13). This happened when they were “buried with Him in baptism, in which you were also raised with Him through your faith in the working of God, who raised Him from the dead” (2:12). Of course, baptism saves no one by itself, but this text and others make it clear that God does save us through Jesus at the point of baptism (Galatians 3:26-27; Acts 2:38, 22:16 and more).
What Paul wants to do in 3:1 is for the Colossians to think about the implications of their baptism. Their baptism was clearly a response to God’s saving work in Jesus at the cross (2:14-15), but it does more than look backwards, it also points forward and that’s what he wants to discuss here. What follows is much the same kind of teaching that Paul shares with the disciples at Rome in 6:3ff of that letter, only as his discussion in Romans related to their circumstances, so Paul frames his teaching here to address the Colossians’ needs.
That is why he tells them the consequence of being baptized is that you “set your hearts on things above, where Christ is, seated at the right hand of God” (v. 1). in keeping with their need to see the supremacy and all-sufficiency of Christ, Paul reminds them of Jesus’ exalted status and the fact that they have been raised with Him! When they were baptized, they were forgiven, made alive and whole, became part of the kingdom of Jesus (1:13)—and they were raised with Him. He will go on to say that their lives are now “hidden with Christ in God” (3:3).
As our English friends say, this is gob smacking! There is some sense in which those who belong to Jesus have left this world. Our bodies are still here of course, but our hearts/minds (see v. 2) are where He is. We still live on earth, but we’re now citizens of heaven (Philippians 3:20-21).
This is to be reflected in how we think and act. This is exactly what Jesus was talking about when He told us to pray, “Your kingdom come, Your will be done, on earth as it is in heaven.” Being a new creation means that we join with God in making all things new and it begins with orienting our hearts and minds.
God wants us to act up and that is how it happens.