It's often said that the Old Testament, especially Genesis, teaches a God of justice, in stark contrast to Jesus, who teaches a God of forgiveness and love. It is a lie, of course. The God of the Old Testament does all that He does out of love; and the Father of Jesus needs to satisfy justice as well as love; that's why Jesus had to die. I used to think that only those who never read the Bible could fall for this fallacy. But experience has taught me otherwise. Why is it so common?
I think it comes partly from misunderstanding the literary style of Genesis. It is not meant to be psychology, either of God or humanity. The modern style of storytelling emphasizes psychological motives and scrutinizes inner consciousness. This is simply not the style of premodern writing. Augustine's Confessions is the only personal introspective autobiography in premodern literature.
Thus the “wrath of God” is not meant as a description of God's own private feelings, but of His public deeds, of how those deeds look to fallen, “wrathful” man. Psychologically, this is “projection”. When God gave Lady Julian of Norwich a “showing” of His wrath, she said, “I saw no wrath but on man's part.” (Peter Kreeft)