Ezek 22:26 God seems to be upset with the priests who have made no
difference between the holy and the profane.  This brought to my mind a
sermon I heard recently in which the speaker said "God's second name does
not begin with a D" referring, I believe, to use of God's holy name and
titles as swear words.  I was also reminded of the experience of Moses at
the burning bush when God told him "Take off your sandals, for the place
where you are standing is holy ground."

These and other texts seem to imply that God's people must treat holy
things differently from other "common" things, or "make a difference"
between holy and common things.

The obvious questions are 

What makes something holy? and How are Christians (primarily) supposed to
make this difference between holy and common things?  (e.g. God's name,
the Holy Spirit, the Holy Bible, etc.)