Most important word in the Bible

"Some years ago the great Swiss theologian Karl Barth was asked what was the most important word in the Bible, the questioner no doubt thinking that Barth would say 'love' or some such godly quality.  But instead Barth answered, "Hyper." In Greek, hyper is a preposition, meaning "on behalf of" or "in place of" another.  Barth called this the most important word because it signifies that the death of Jesus was in our place and for us.  He died so that we might not have to die spiritually."
 - Boice on Christ's death for sin.