What does Romans 3:25 mean?
The previous verse concluded with the statement about God's gift of grace. God's justifying of us—His making us righteous—came through the redemption that is in Jesus.Now Paul writes that God put Christ, His Son, forward as a "propitiation." This is yet another weighty and meaningful theological word. Propitiation comes from the Greek term, hilastērion, which means "sacrifice of atonement." God literally gave Jesus over as the blood sacrifice to pay the debt of (or to atone for) our personal sins. It's also important to note that this same term, hilastērion, is used in Hebrews 9:5 to describe the "mercy seat:" the place on the ark of the covenant where blood was placed for atonement (Exodus 25:17).
In other words, God expressed all of his righteous anger against our sin on Christ on the cross to the point of death, paying what we owed in full. This gift of the sacrifice of God's own Son to atone for our own sin must be received, Paul writes. We must receive this gift by faith. In fact, Paul will make clear through the rest of this letter that faith in this gift, this act by Christ on our behalf, is the only way for anyone to be made righteous before God and to be included in His family.
This brings us to a great question: Why did God do this for us? Why would He do this? The answer Paul gives is that it is because of God's righteousness or justice. God did not say, "Your sins don't matter; I'll just ignore them." He fully poured out His justice against sin when sinless Jesus was sacrificed for sin on the cross.
Paul shows that this includes the sins of the past, before Christ died on the cross. He writes that God "passed over" those previous sins in an act of divine patience and perfect timing. Again, it's not that God failed to punish those old sins. It's that He stored up His punishment and poured it out on Jesus to fully satisfy the payment for those "former sins."