I believe the concept of Jesus being separate from God while simultaneously not being separate from God is a concept lost people may have a hard time understanding.Okay, I can go with a potential misunderstanding. Let's talk it out. Think it through, as it were.
The phrase "spiritual truths" is pretty broad. What spiritual truths are you talking about?
Romans 1 makes it painfully clear that spiritual truths such as God's existence and right and wrong are well within the grasp of even reprobates as disgusting as homosexual and murders to the point that they are "without excuse".
Now, I agree that there are some spiritual truths that are outside the bounds of what an unbeliever can grasp but not because God has yet to sprinkle some wisdom dust on their head or perform some sort of super-natural miracle that transforms their mind into something substantively different such that it makes things understandable to them. It isn't that at all. It's simply that the requisite suppositions that certain truths are predicated upon are not present within the mind of an unbeliever. Indeed, this is true of many believers as well!
For example, it makes no sense to try to have some sort of substantive discussion, much less a debate, with an unbeliever about the idea that believers are identified in Christ and what that truth means for the daily life of a believer. There isn't any common ground upon which to base the discussion. There's no way for the unbeliever to have anything other than a very superficial idea what that topic is even about. It would be like discussing the penthouse suit at Trump Tower with someone who had never been within a hundred miles of a city. It isn't that they are incapacitated, its that they have nothing upon which to build the necessary premises that the subject is based on.
The concept of God becoming a man very simple does not fall into this category. As I said before, it is among the most basic principles of the whole Christian faith. It is literally the milk (see I Cor. 3:2 & Hebrews 5:12-13). You cannot even rightly present the gospel to an unbeliever without discussing the fact that God became a man so as to die for the sins that we are guilty of. Right?