[L]iving in believing community is one of the central instruments that a loving God has given to us to prepare us for that great day. Living among fellow sinners, learning how to deal with it properly, is the principal form of industrial grade sandpaper that the Holy Spirit uses on us. But many pietists, including many educational perfectionists, withdraw from that treatment, shrinking from it, and all in the name of maintaining their smooth surfaces. But hiding the rough cut lumber in an unlit shed is not the same thing as sanding.
—Doug Wilson, [Holy Ghost Industrial Grade Sandpaper]