Only because whatever god does cannot be called "sin", for the reason that "anything that is against god's will is labeled as sin". This type of concept may make a deity immune to "sin", as it calls it, . . . but it doesn't automatically make the same moral/ethical. There is little purpose for "wrath", especially when "wrath" is a state of great emotional upheaval brought on by an unforseen input.
Many people like to say, "it is the same as the dad who knows that his child will do something wrong, yet still gets angry when he does". This is non-sensical, and shows a lack of foreknowledge or [more importantly] caring that this child is going to do something wrong. If I know, without a doubt, that someone will do something wrong, and I have the absolute power to stop them, yet I don't, then I have some culpability in the action committed.
TOO often, I see VERY human like characteristics being placed upon this god. It seems more like a concept of people who WISHED they could impart their impotence . . . OMNIpotently upon those who wronged them, and felt that their god could.
I'm impotent, he's omnipotent.
I'm limited in my understanding, he's omniscient.
I'm limited in where I can be, he's omnipresent.
In the same way, . . . I'm unable to defeat those who are conquering me, but my extreme anger [wrath] is insufficient to do anything about it, therefore, my god will burn with his wrath against them and bring them to submission.
I know that many will disagree with me on my point, . . . being a christian forum site, I expect that. . . . . . . . . but I won't be angry about it! ;)