Okay, yes that is straightforward enough.
I'm unable to answer this until I figure out what I mean by ideas (in general), by God and if it is even possible to say we can have an idea of God.
I had a stream consciousness response which I removed where I debated the whole thing.
Upon further reflection, I think I need to say that God is not completely unknowable, it is possible to have an idea of God.
In my Zen training, I was taught that my ideas are only mental constructs and never grasp the thing itself. My ideas don't exist. Even concepts like good and evil are just concepts. Reality just is as it is. God even more so is beyond such concepts.
Yet, I think I must listen to why I left Buddhism. I experience that God is not merely a passive, philosophical abstract. Rather I think that this Absolute is actively loving, actively sustaining, actively illuminating. So our idea of God comes from God thru illuminated reason and other illuminated faculties.
Kabbalah has a strange position that as an ex-Kabbalist I need to consider. Ein Sof is the Source, the First Cause but is ultimately unknowable. We only know God thru Hus emanations, which aren't Him but reflections of Him. Many theists too are apophatic theologians and say we know about God mostly thru negation. Yet they still cling to revelation and their respective traditions.
It doesn't make any sense to say God is completely unknowable yet illumines or loves us or creates us. For we then know at least that much about Him in so far as He is active in our experience. God can definitely be mostly unknownable, we only perceive a small sliver perhaps.
Another issue to address, which is what you point to, is if God grants us the idea of God then why is our ideas so different from one another? Is it because as religions would suggest, the majority are impaired or mislead and only one certain group received it correctly? Unlikely.
Or is that we are given only the most basic sliver that mankind has added all sorts of vain imaginings too? Most likely
Or is it the blind men and the elephant where depending on each ones context and personality and baises, everyone sees the Truth but differing aspects as a prism captures only part of the spectrum? Maybe, but this has points for being a charitable view.
So I need to fully answer these questions before I arrive at what you are asking.