God presented Him as an atoning sacrifice in His blood through faith, in order to demonstrate His righteousness, because in His forbearance He had passed over the sins committed beforehand.
KJV
Whom God hath set forth [to be] a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
ASV
whom God set forth to be a propitiation, through faith, in his blood, to show his righteousness because of the passing over of the sins done aforetime, in the forbearance of God;