We are being trained and prepared in this life for eternity in the Kingdom of God.
After our resurrection at the return of Christ, after the millennium and after the white throne judgment is over, after the third resurrection and the destruction of the wicked in the lake of fire, when the new heavens and new earth are here, will there be anger in the Kingdom of God? Will there be any anger among members of God's family for eternity to come?
Will we see any anger a million years from now?
I don't think so.
Not all anger is wrong. "Be angry, and do not sin..." (Ephesians 4:26). There is such a thing as "righteous indignation" (2 Corinthians 7:11). We should be angry with sin for example, especially our own sins when we see them, and there may be times when we should be angry with ourselves for some of the stupid and wrong things we do, especially if that anger towards self arouses a determination in our mind to never repeat the mistake. And sometimes it is right to be angry towards others.
God Himself becomes angry (Psalm 7:11). Christ became angry at times (Mark 3:5).
But while we may become angry, occasionally, the tendency to become angry should not become a major part of our character and personality. We should not harbor and nourish the attitude of anger. And that is a danger. We should be slow to anger. "The Lord is merciful and gracious, Slow to anger, and abounding in mercy" (Psalm 103:8).
We should learn to give a soft answer to those who become angry with us and not return anger for anger. "A soft answer turns away wrath, But a harsh word stirs up anger" (Proverbs 15:1).
God teaches us to pacify those who are angry by answering softly. Did God practice what He preached?
Look at the ending of the book of Jonah. Jonah became angry with God twice. How did God react? He did not return anger for anger but answered Jonah's anger by patiently reasoning with him. "Then God saw their works, that they turned from their evil way; and God relented from the disaster that He had said He would bring upon them, and He did not do it" (Jonah 3:10). "But it displeased Jonah exceedingly, and he became angry. So he prayed to the Lord, and said, 'Ah, Lord, was not this what I said when I was still in my country? Therefore I fled previously to Tarshish; for I know that You are a gracious and merciful God, slow to anger and abundant in lovingkindness, One who relents from doing harm. Therefore now, O Lord, please take my life from me, for it is better for me to die than to live!' Then the Lord said, 'Is it right for you to be angry?' " (Jonah 4:1-4). "And the Lord God prepared a plant and made it come up over Jonah, that it might be shade for his head to deliver him from his misery. So Jonah was very grateful for the plant. But as morning dawned the next day God prepared a worm, and it so damaged the plant that it withered. And it happened, when the sun arose, that God prepared a vehement east wind; and the sun beat on Jonah’s head, so that he grew faint. Then he wished death for himself, and said, 'It is better for me to die than to live.' Then God said to Jonah, 'Is it right for you to be angry about the plant?' And he said, 'It is right for me to be angry, even to death!' But the Lord said, 'You have had pity on the plant for which you have not labored, nor made it grow, which came up in a night and perished in a night. And should I not pity Nineveh, that great city, in which are more than one hundred and twenty thousand persons who cannot discern between their right hand and their left—and much livestock?' " (Jonah 4:6-11).
Much of the time, our anger is not "righteous indignation" inspired by God, but unrighteous wrath inspired by Satan. "So then, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath; for the wrath of man does not produce the righteousness of God" (James 1:19-20).
We should not let anger dwell in our minds for a long time. "...do not let the sun go down on your wrath" (Ephesians 4:26). In this verse, God is not telling us to be like Joshua and pray that the sun not go down so we can remain angry. He is telling us to end our anger quickly. I suppose I could joke and say, it is better to get angry 2 minutes after sunset rather than 2 minutes before sunset - that way you can stay angry for almost a whole day and still stay within the letter of Ephesians 4:26. You'll have a whole day to get over it. But then, the person who makes us angry could plan to get you angry two minutes before sunset. (Next time your husband or wife starts to get angry, just before sunset, say, "watch out, it's almost sunset.)
But God's purpose is that we get over our anger quickly. Our anger hurts us as much or more than it hurts others.
We do not need to make anger a permanent part of our character. Why? It will not be needed in the Kingdom of God for eternity. It is a temporary, "throw away" emotion, something that when used righteously and kept under control can be useful when dealing with sin. But when sin is gone, there will be no need for anger.
Anger is caused by sin. Righteous anger can be a response to sin, and unrighteous anger can itself be sin. "But I say to you that whoever is angry with his brother without a cause shall be in danger of the judgment" (Matthew 5:22). But when sin is abolished, anger will no longer be useful. Probably, God Himself was never angry until Lucifer committed the first sin. And when Satan and his demons are permanently put away, when sin is banished from the universe and from God's Kingdom, we will never again have any need for anger.
God is building our character to prepare us for an eternity without sin, without tears, and without anger. "And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away" (Revelation 21:4).
Let's not make a tendency towards anger a part of our character. We won't need it in God's Kingdom. Instead, let's develop love and faith (1 Corinthians chapter 13, Hebrews chapter 11), attributes of character that we will be using for eternity.
Let's be slow to anger and quick to put our anger away and replace it with love and faith.
Let's remember that people sin because this world is enslaved by Satan, and Satan tempts even us in the Church to sin and make mistakes, and only God can rightly judge how much blame attaches to Satan and how much to the human who sins.
Let's not repay with anger, but trust the righteous judgment of God (Romans 12:19-21). Let's replace anger with mercy, and have a merciful attitude towards others as we want God to be merciful to us. "With the merciful You will show Yourself merciful" (Psalm 18:25). "For judgment is without mercy to the one who has shown no mercy" (James 2:13).
On the other hand, if you want God to have an angry attitude towards you, then nurture and develop an angry attitude towards others.
"Do not be deceived, God is not mocked; for whatever a man sows, that he will also reap" (Galatians 6:7).