In Colossians 1:12-14 Paul writes of our position being transfered from a domain of darkness to a domain of light:

giving thanks to the Father, who has qualified us to share in the inheritance of the saints in Light. For He rescued us from the domain of darkness, and transferred us to the kingdom of His beloved Son, in whom we have redemption, the forgiveness of sins.
(Colossians 1:12-14)

This passage is in the middle of a recording of a prayer that Paul regularly prays for (at the very least) the church in Collosae [starting in verse 9]. Paul has already prayed for their spiritual growth and for their walk to be maturing, but then he gives thanks to God for a list of important things: God’s qualification of us to be sons (and daughters) that we might be inheriters of God’s Holiness. Paul continues to be thankful for our having been transferred from the domain of sin, the flesh and ultimately being children of Satan to being in the domain of Christ (how just happens to be our redeemer). Paul’s last bit of thankfulness is tied to our redemption in that we can be thankful for the forgiveness of sins.

In short I think there are several applications of this passage, but one that really stands out is that due to God’s work we are set aside into His Holiness so no matter what we do, we have God’s holiness that surrounds us. Since we have that holiness, since we have our sins forgiven we need to walk in that holiness, but if we somehow fail to walk in that then we need to not dwell in guilt, shame and self flagilation, and instead we need to return to our focus on God and His Holiness. We are transfered and the legal documents required of us to be heirs is done, signed, sealed and official. You can’t undo your salvation and God’s grace is completely sufficient. He’s not looking at your forgiven sins, why would you?