A few seminary posts:

I think there is information to be learned in how Jesus revealed Himself. Since God did come and show Himself - through Jesus - we should see how He showed Himself.

I think there is a part of God that wants people to want Him. He wants to see if we really want Him or only when it is easy to have relationship with Him. Since God valued sacrifice over and over throughout the Bible (chiefly in the death of Jesus), He wants to know if we want Him only when He is easily revealed or if we love Him enough that we are willing to sacrifice anything in order to have more of Him and His presence. In Luke 24:28 and Mark 6:48, it appears that Jesus has no problem taking some initiative with His followers, but eagerly desires them to pursue Him. In James 4 we see that we are to draw near to God and He will draw near to us. I think God reveals more and more of Himself as we fall more and more in love with Him. Brian Johnson has a lyric in his song We Believe that says, "You reveal your secrets and all of your mysteries to those who have fallen completely in love with you." I am firmly convinced that God is looking for those who will decide that He is worth whatever sacrifice to be made to truly know (in my mind, this should be an easy choice to make as there is nothing in this world that satisfies for longer than a minute or two, and living a narcissistic life for pleasure is extremely empty and eventually depressing). I think the apostle Paul was definitely one of those with the remarks made in Phil. 3 about considering everything a loss in comparison to knowing Christ. So God will show more and more as He is invited and pursued (both individually and corporately). To try to uncover all of God without seeking to know Him is to almost treat Him as a prostitute: only to use Him for one's own benefits. The reality is that God's eyes are looking to and fro throughout the earth looking for someone who has truly fallen in love with Him and wants to live out His desires - rather than seek Him to bless what they want done. While these things might be the same, the approach is radically different. In the former, one lives in peace and joy with the Lord as they see Him fight the battles for them (sure, it might be on His timetable and not ours but He still provides the ability to remain content with the unresolved issues of life). The latter leaves one wondering why God is holding out on them and is more like manipulation. I think the end of 1 Corinthians 2 shows how the way to understand God is through the Spirit. Those who spend very little time filled with the Spirit will probably spend life asking a lot more questions than uncovering answers that come through His revelation and revealing of Himself. This is not to say anyone ever gets all of their answers solved. Bill Johnson has said something along the lines of, "Any God I could absolutely understand is probably not one that I want to serve."

So, to summarize, I think, in general (this is not a debate about unreached people groups), the Lord shows enough to invite in relationship and waits to see who are hungry.

One issue that I hear mentioned in this thread is in regards to how we respond when we blow it. I think there are two sides that are out of balance.

I think we can look at numerous people in the Bible who did not care at all about the sin in their life. They continued to live in ways that were contrary to what God had and could care less. The consequences of this spiritual apathy cost many of them very dearly. Many of the OT kings would be example of what I am referring to.

However, equally out of balance is living in guilt and/or shame. Martin Luther is a perfect example of a man who spent a lot of time with a guilty conscious. It is very easy for a Christian to live in a cesspool of guilt, think that this is the way that they are called to holiness and essentially be taken out of being used by God because of a never ending internal witch hunt. I remember talking to a guy who thought that guilt and shame were good for him. I asked him if they ever caused much change in his life for the positive. It did not appear that there was much internal change as a result of what he thought was good for him except picking a few external bad pieces of fruit. There was no internal heart change that came from guilt and shame. Perhaps the only reason why he thought they were good is because they temporarily pulled him out of spiritual apathy. However, guilt and condemnation are out of balance and unable to free people just as much as spiritual apathy is.

I think the biblical response is neither of these two. While different issues require different responses, I think things that have greatly helped me are:
1) Take sin seriously. Repent seriously, not flippantly. Then line up with truth. 1 John 1:9 says that he has now cleansed me from ALL unrighteousness. Therefore, line up with truth and do not claim that Jesus' work was not enough by trying to punish myself. But, at the same time, do absolutely, positively whatever it takes to have change. There is no cost that is not worth paying for freedom.
2) Find someone who is walking in victory in what I want to walk in victory in. Learn from them. Discover how they got to where they did. Do not assume that because I have not experienced victory on my own with God or in talking to people that similarly struggled that this is simply "my cross to bear" or "my thorn in the flesh." I have seen some say that some things are impossible that I see others that are walking in victory over.
3) Trace back mindsets. What were my mindsets (lies I was believing) that prompted the negative fruit. Change the mindsets to truth.
4) Approach the Christian life holistically. The Spirit empowers us for everything, not just a few things. Therefore, all of life must be changed, not just the sin issues I do not like.
5) Realize that we are not internal producers of righteousness. In other words, our striving does not produce much of any kind of breakthrough. It is through relationship and changing what I believe that causes breakthrough.

Those are just a few things that come to mind, and obviously not even close to comprehensive. However, I only wanted to note the difference between guilt vs. spiritual apathy as near as I understand.