"...Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus." Romans 3:25,26
As I was reading this on Sunday - our epistle for Reformation - the thought struck me that what the Blessed Apostle was saying here is that God put forward our Lord Jesus Christ as the propitiation to show the divine righteousness or justice, His fairness if you will. Because He had passed over sins in the past without bringing upon the sinners the doom He had forewarned (even think of Adam in Paradise!), He might well appear to be an unjust God. Capricious even.
Yet the one sacrifice of our Lord manifests that God is just - in that He leaves no sin unpunished - for all our sins are laid on the divine Son who bears them in His own body before the holiness of the Divine Majesty and that holiness wipes them out, but of course, it cannot wipe out the person of the God-Man. The result is that God can be and is both JUST and yet the JUSTIFIER of the person who trusts in Christ, in His atoning blood.
Now, you may say, "Well, duh." But it takes a while for things to get through this thick skull. See, I should have sweated through Romans instead of opting for a summer class on Galatians!