You rightly recognize the audacious claims of Christians and others who assert they possession knowledge of ultimate reality and God. (It is a bold statement to claim such knowledge about God and reality.) You also rightly recognize that competing statements about God (Jesus is God and Jesus is not God for instance) cannot both be true at the same time and in the same way (this would violate the law of non-contradiction).
But, you overlook the fact that your position (the position that says ‘knowledge about God and big questions of existence are outside of our access’) is itself an AUDACIOUS metaphysical claim. For you are claiming to know that this knowledge about God and reality is out of reach and inaccessible—how do you know this?—and you are claiming that every other view is wrong—you do so by asserting that religions are just cultural [mis]understandings of God which are not tethered to objective truth.
Another shortcoming in agnosticism is that it has to borrow from the Christian worldview to make knowledge claims. We see this in how an agnostic holds to the trustworthiness of sense perception, the validity of logic, and the uniformity of nature—all things which rely on the reality of the God of the Bible who established the world in such a way that these are possible. (How could we know whether we could possibly trust such things unless they were created and designed and upheld by God who has given to us so that we might have real knowledge of the real world that is there?)
Your longing for knowledge about God and reality is something that should be encouraged, not written off as impossible. Agnosticism offers a freedom, the freedom to live how we wish and think how we wish. It is offered up because it is asserted that no one can really know what God is like or how He would have us live, so we are all free to live any way we want. But such a freedom prevents an even better type of freedom—the freedom to know the one true God who is there, the freedom to know His love and enjoy a relationship with Him.
Jesus gives us real and true knowledge of God and ultimate reality. He reveals God (John 1:18) and is himself the truth (John 14:6). He rescues from the false shelter of agnosticism and brings us into the true shelter of knowledge in Himself. He died for our rebellion and unbelief, and brings us into the family of God and true knowledge of God. This is the knowledge we really need, and here there is freedom, joy, and everlasting life.