There is a war going on. All talk of a Christian’s right to live luxuriantly “as a child of the King” in this atmosphere sounds hollow-especially since the King Himself is stripped for battle. It is more helpful to think of a “wartime” lifestyle than a merely “simple” lifestyle. Simplicity can be very inward directed, and may benefit no one else. A wartime lifestyle implies that there is a great and worthy cause for which to spend and be spent (2 Corinthians 12:15).
John Piper