What is a relationship?

I was recently reading a blog, and the issue was dealing with why God is hidden. This was in relation to many agnostics/atheists saying that they had looked quite hard for evidence, and had found none. God has to remain hidden so that the ability people have to make moral decisions isn't coerced in any way. Furthermore, if God did make Himself so easily visible, it would interfere with the free will and autonomy of humanity. They would respond to God due to self-preservation and fear of punishment, as opposed to wanting to get to know God just for the sake of knowing Him.

I've seen this argument a few times, but it was only this past month that I realized I was confused over portions of it.

Any time we have a person point out the less than ethical Christians throughout history as to why some people don't view Christianity in a positive light, or why they might feel religion is harmful, one of the responses is inevitably the idea that many will claim to follow Jesus, but that at the day of judgment, Jesus will say something along the lines of how they are to depart, for they never knew him. Even though these people claimed to preach about him, do good works in his name, expel demons -- didn't matter. Jesus didn't know them.

So, obviously, the departed people didn't truly know God or have a relationship with Him. They had knowledge of God (presumably, given what they claimed to have done). But that knowledge of God, and that claim or belief to follow God, wasn't enough to ensure salvation.

So, if it wasn't enough in this case, wouldn't the same principle apply if God made Himself so completely obvious to everyone? If it's not enough to simply believe in God and try to follow Him, then how is any sort of revelation an issue? Why remain hidden? Surely, since God would know the inner workings of people, that if someone was only not robbing others out of punishment, but very much wanted to rob others and wasn't "convicted" of that sin or anything, such a desire would be factored into the equation.

Another issue I have with this argument is the assumption built into the answer. There are plenty of people who genuinely wish God was real, only don't see any evidence for the case. They do want a relationship with God because they want the unconditional love, or they want a purpose in life, or they want to be a better person. They've prayed, they've read the books, they've searched ... and they feel that the only honest solution is to be an agnostic or atheist, due to what they see as the lack of evidence.

So if God ceased to remain hidden in their cases, they would respond to Him, but not out of a fear of punishment. Except the argument contains the implication that those who claim God is too hidden would only respond to a revelation out of a fear of punishment.