Wrath of God
God's anger is completely disinterested. God is not angry for His sake, but for ours. We cannot be happy when sin separates us from God, from our neighbor, and from our true self. We are made for love; sin cuts us off from love. God hates that which is destroying us.
God's anger is perfectly proportionate to the evil we have done.
God's anger has a goal and does not last forever: God wants us to repent of our sins and repair the damage we have done. This is our bliss!
The fact that we can easily tell that someone is breaking God's law or the laws of the Church does not give us freedom to hate or despise them. They and their sins are God's problems, not ours. We are not God. If we have some say in the matter, we can voice our protest; if not, we can keep peace in our hearts and pray for them as Jesus commands us to pray.
God never rages. He does not lose control of Himself. He does not lash out blindly. He does not lose His cool.
The suffering of the souls in Purgatory will come to an end. They are making progress toward eternal bliss. They suffer only as much as is necessary for them to live in perfect happiness with those whom they have harmed and no more.
People systematically misread the Old Testament. There is much more to it than the wrath of God. They hear what they want to hear. They don't notice the proclamation of God's glory in all of creation.
It is the Testament of Nature. The theme of God as Creator and Lord of all things is more muted in the New Testament because that is so focused on what God has done for us in Jesus. The Old Testament is the answer to the canard that the Church does not believe in the omnipresence of God.