Strangers, pilgrims, sojourners, aliens. That's what Christians are. The reminder that we are (this) is a call to (that): a different lifestyle. Since we are this, we ought not act like that.
Beloved, I urge you as aliens and strangers to abstain from fleshly lusts which wage war against the soul.
1 Peter 2:11
We are just passing through this place, now that we are citizens of a different place. This is not our home. To put it bluntly, we've been touched by God who made us in His image, and now we have more in common with God than animals, so we ought now act like animals any longer. Although we still live on the dirt, next to the animals in human bodies subject to the wear and tear of earthly life.
We live down here, but we belong to up there. We will live down here for a short time, but we will live up there forever. In the light of this, we ought to act like who we are, not where we are.
This is a call to holiness, that just makes a lot of sense. You act a certain way because
of who you are. You walk in your identity. It must take practice and reminding, otherwise we would not have or need verses like this one and I would not be writing on it.