In Col 1:14, the particular feature of redemption that Paul wishes to highlight is a pardoning of sins. Notice that Jesus did not come to immediately liberate us from the effects of living in a cursed world, although that comprehensive, final salvation will happen in the end. This means he did not come to presently redeem us from difficult days with work or kids, from financial or health issues, or family conflicts, but from our sins, thus decisively solving our greatest problem.
Our sins earned us the death penalty in the divine courtroom, but we have been released from that sentence! It has been permanently cancelled, never to be brought against us again! This is why we can give thanks to God in all things because nothing can change our redeemed status. How so? God didn’t just arbitrarily decide to redeem his people from their sins for his holiness would not allow it; there had to be a payment made in the form of a sacrificial lamb. The word redemption actually implies the necessity of a ransom payment.
Paul does not conclude this section at v.20 without highlighting the cross of Christ. His blood shed at the cross secured this redemption and all of these other benefits previously listed. This is in spite of the fact that we were entirely unworthy of any mercy of the Lord; we were enslaved to the darkness of Satan’s dominion; and we had the full weight of our guilt of our sins on our heads.
So do we have any legitimate reason to neglect to always give thanks to God with joy?