chief cornerstone

I was reading in Eph. 2 today.

"Consequently, you are no longer foreigners and aliens, but fellow citizens with God's people and members of God's household, built on the foundation of the apostles and prophets, with Christ Jesus himself as the CHIEF CORNERSTONE. In him the whole building is joined together and rises to become a holy temple in the Lord. And in him you too are being built together to become a dwelling in which God lives by his spirit." 2:19-22

"Our citizenship is in heaven." Ph. 3:20
I am a foreigner here. It's like being black in Bend. (no racism meant there.) There are a few others out there, but they are few in far between. You have your immediate family; they surround you. But beyond that, you are placed in a world far from all acceptance. The apostles and prophets began this journey long before I did. Many others have walked and finished this voyage. But without the grace of Christ, this pilgrimage would be ineffective.
You must live in grace, to walk in faith. Without successfully using your faith in work, then it dies. So how do we live in grace and potently walk in our faith?
Christ Jesus is our chief cornerstone. The perfect example. The foundation. He is the most valuable player.
"Everyone who falls on that stone will be broken to pieces, but he on whom it falls will crushed."
Break me down, to build me up in you. This verse from Luke has stuck in the back of my mind all weekend. If we fall upon the cornerstone, Jesus Christ, we will be broken to pieces, but if he falls on us, we will be crushed. What's the difference between being broken to pieces and crushed? Can something broken to pieces be put back together?