God is not a human being with human passions.
God is unchanging. Becoming angry or offended is a change.
The language describing God's wrath and anger and jealousy etc. is, I believe, used so that we human beings can relate to what is being taught.
It is my understanding that all the "wrathful" actions taken by God are didactic; they are done that we might learn that our actions, which brought about the wrath of God, as self destructive. It is similar to when a parent tells his young child not to play in the street. After a few warnings, if the child continues to disobey the parents command, the parent may spank the child. In that way, the child will relate disobedience and the self-destructive behavior with pain. The child will perceive the parent as being angry with him.
So also, God, from time to time, has "spanked" individuals and even all of mankind in order that they, or others who observe or learn of the "spanking" (the flood story is essentially universal), would learn not to disobey by behaving in a self-destructive manner. The objective of the wrath is than people do not end up in hell just as the objective of the child's spanking was that he not be killed by getting run over by a truck.
In both cases, the "wrathful" action taken was an act of love having the objective of preserving the life of the subject of the wrath.
Anyway, that's the way I see it.
iakov the fool