I'm not sure why someone deemed it necessary to fill these openings with cinder blocks, but I'm reminded of the two ways we block God in or out of our lives.
First, the obvious: all of us, at one time or another, have probably blocked God out of our lives. Especially if we're doing something (i.e. "enjoying a lifestyle") that we believe God would reject. If you've spent any time at all in the Old Testament, you know that when God is angry, bad things happen.
Because God has given us the freedom to choose Him (the power is in the choosing!) we are also free to ignore Him - to hold our hands over our ears and sing "la la la la la" as if we can outlast His persistent will for us. We can busy ourselves with our lives and not give Him a second thought. We can put cinder block across any mental openings to ensure that His will can be denied. I've done this. I know how it goes.
We can also close God "in" by defining Him in such a way that we are comfortable. Yesterday our church was packed to the rafters. I'm hoping that some of the newcomers are not just "Chreasters." I'm hoping that they felt the Spirit moving in our midst and that they feel called to return to our blessed congregation. That having sipped from the well they recognize that God's son is the only source of the living water. Interesting that so many people celebrate his birth and his re-birth, but they miss out on celebrating his life. They've put God in a box that they visit once or twice a year. They might think about God once in a while, but they don't recognize the life changing presence (or maybe they fear the impact of embracing the Spirit?).
Have you boxed God in or closed God out? Are you willing to let God fulfill his promise to you? He has told us that if you seek Him, you will find Him. If you knock, the door will be opened. No amount of cinder block can keep Him from you. Invite Him in (or let Him out of confinement) and He will not just open the doors, He will blow down the walls.