Indeed. You'll notice from what I said, though, that I wasn't saying I assumed anything of the sort, but that "many theistic claims" did. So if God is supposedly perfect, and you find imperfections, either God isn't God or what those claiming those attributes for him are saying is false ... and is therefore not the word of a God.
That is not an argument against (or for) the existence of God, but of what those religious practitioners have to say about it.
Therefore, if you cannot rely on what the established churches claim is the word of God, then you have to seek a direct relationship with Him yourself ... and draw conclusions and/or opinions as a result of your experiences.