God is the Judge. We will be treated unjustly. Our anger is usually a response to an actual wrong, but what is more important is how we react to that wrong. We may lodge a complaint, have a personal conversation with an individual, or deal with the desires or sins of our own heart. Regardless of our course of action, God, the Judge, will handle all offenses and He will act rightly and justly.
1 Peter 2:21-23 records the unjust suffering that Jesus endured. It also records that He did not commit sin or use deceit in responding to the wrongs. He chose to entrust Himself to Him, God, who judges justly.
In becoming man, Jesus gave up His right to judge the world, but He gave that right to His Father. He trusted His Father. We have the same Father who continually judges justly today. Do we trust Him in the same way Jesus did? We are freed from anger when we leave the injustices we endure in His capable hands.
At times we want to know how God will judge wrong doers, but our trust is not in knowing how they will be judged, but our trust is in the One who judges all men. We trust Him to do what is right. Anything other than trust sets us up as His judge.
We can trust that His judgment of others, as well as of us, will be better than we could have ever imagined and our response will be one of worship. We will see in the end that His way is best.
At the core of the belief that we must handle injustices on our own is a lack of faith in God's presence, care, sovereignty, and justice. We need to turn our trust towards Him and know that He will deal justly with all men. He is trustworthy.