God: "I looked for someone to take a stand for me, and stand in the gap" (Ezekiel 22:30)
In the past, God had left sins unpunished. He could conceivably be accused of overlooking sin since He had not required punishment for it. Now, however, He has put forth Jesus. This proves that God is just (His wrath required the sacrifice) and that He is the justifier of those who have faith in Jesus (His love provided the sacrifice for them).