The understanding about Jesus and God is a issue not related to cognitive ability. A perfect example was brought up today.
Our visual system can be in perfect working order, and we can explain how that process works in perfect detail to anyone, but if we do not have light coming into our eyes, we can not see. If we live in total darkness, if we have blinders on, if we are wearing a filter over our eyes that prevents light coming in, we can not see.
Likewise with God, we need to have the light of God shine into us in order for us to see Him. We can have all the cognitive understanding, we can get all the knowledge, but until God shines on us, we cant see.
I say this with full knowledge that God is not shielding Himself from us, but it is always the opposite. So many have blinders on, or their heads buried, or are just living in darkness yet they don’t realize, since they live for themselves and are perfectly content to live in that reality.
There is the question of whether God can harden someones heart, and while i did not listen to the video that was presented in this thread on that topic, i think that is a question best suited for people above my pay grade. I do know God is omniscient and omnipotent and if He knows someone will never come around to seeing Him, then there might be situations where he does harden a heart to maximize benefit for His people. However, like i said, that is above my paygrade, and beyond the scope of this post/thread.