God once told people not to create idols, even idols representative of Him. Those “graven images” could not define or contain God and only served to limit God in the eyes of those who would create or worship the image. Our self-constructed mental images and theologies can be every bit as much an idol as a statue, trying to box up and limit God- creating an image of Him we can understand, predict, control, be comfortable with, intellectualize, and philosophize.
Don’t get me wrong, I think theology can be useful and glorifying to God. Theology is the defining and systematization of spiritual truth. It helps our little brains get a handle on who God is, who we are, and the relationships between God and us and the universe. Theology takes the Bible which was written for a much different world view and helps to distill it into a form we can better comprehend. It gives a framework or a lens that we can use to make sense of the universe around us, a passage from scripture, or our interaction with the spiritual.
However it is those same things that make theology dangerous. When we latch onto a particular theology (and there are many different competing theologies) then we can blind ourselves to anything outside our theology. If one is a Calvinist (a particular school of theology) then he/she will understand things one way. If one is a Mennonite, then he or she will understand things a different way. If one has little formal theology, one still has some sort of theology that a church, an author, a respected person, or even the ambient culture has imparted. Each theology tends to highlight those scriptures and experiences that support it while downplaying or explaining away those that seem to contradict. This can make a person ignore what God is trying to tell them because it does not fit with their theology. And theology can give the impression that I really understand God, I have it all figured out. But in reality I have only created an image of God. One that I can understand, predict, control, be comfortable with, intellectualize, and philosophize about.
Theology is something to hold lightly in your hand. Theologies are only metaphors and all metaphors are flawed and break down. This does not mean metaphors are useless, but we cannot slavishly look to the metaphor. Revelation about God must inform the metaphor not the other way around and we must be willing to change or drop the metaphor if it does not fit with revelation. We cannot truly hold the infinity and holiness of God in mere words.