The writer of the lesson puts it this way:
"We often know enough not to ascribe our security to carnal, worldly things. Our greater, slyer temptation is to place our security in the blessings we readily credit to the Lord.
"Even if our security is in something God has given us -- our gifts, talents, loved ones, church family, consitent victory, passion for His Word -- our seemingly secure mountain ultimately will fall into the sea. We can grow secure in the favor God has shown us, but God's favor and His person are not synonymous. If our trust is in the manifestations of God's favor rather than God Himself, we will crumble like dry clay when He calls us to walk a distance of our journey entirely by faith and not by sight.
"To build on our previous psalm of ascent , God is with us and for us even when His face and His favor seem hidden. Mountain-like security only comes from trusting God, not what He's done for us or given us, however glorious and eternal those things may be." (Masterwork, p.45)