Romans 3:26

he did it to demonstrate his justice at the present time, so as to be just and the one who justifies those who have faith in Jesus.

(v26, NIV)

This is similar to what was said in the previous verse. However, this time the reason is given with regards to God who God is and what he does, not what he has done. By presenting Jesus as a sacrifice, God is just. Proper payment is being made for the sins of the unrighteous. However, at the same time, God is able to be the justifier of those who have faith in Jesus. It is only by Jesus and his sacrifice that we may be justified. We cannot be justified by our own works. We cannot merit it by doing good deeds alone. It is only by faith in Jesus that any of us are justified. So it is by this sacrifice that God is just and the one who justifies those who have faith in Jesus.