Behind the critics cries against God shutting the door of heaven on May 21, 2011 is a basic error of understanding the gospel. The error is that they think God is obligated to give every person an opportunity to hear and receive/reject the gospel. This notion is completely false.
Did God give every person who lived on the Old Testament side of the cross opportunity to hear and either receive or reject the gospel? The answer is absolutely not!
But that was the Old Testament, let's ask about the new: did God give every person who lived on the New Testament side of the cross opportunity to hear and either receive or reject the gospel? And again, the answer is absolutely not!
From 33 AD the gospel did begin to slowly spread out to the nations. But many generations of people lived and died before it ever reached them. Proof of this would be all inhabitants of island nations. People inhabiting pacific islands did not hear the Word of God until only a few centuries ago.
It's simply not true that God is obligated to send forth the gospel in order that every human being hear it and either receive or reject it. That is a completely false (and free will) understanding of things. In fact, we can know that God bears no obligation to those that were not chosen to salvation.Therefore He can shut the door justly according to His perfect program of times and seasons for this world.