I believe that God has revealed Himself to us all, He has left us without excuse, but we all are sinners, and all are dead in our sins and trespasses. We are all utterly fallen and none will ever turn to God unless He first quickens us with new life. How and why He choses each of us is His own perogative, we have no claim on His grace, for we all have rejected Him.
It is not that there are some out there who are wanting to find Him but He will not let them come, it is the fact that none are truly seeking Him, or should I say, none are willing to accept Him when they find Him.
Just my opinion on things, and obviously not one that is needed to be a Christian, nor one I believed when I first came to Christ.