John 17:14

Not of the world (ouk ek tou kosmou). They are "in the world" (en twi kosmwi, verse Philippians 13 ) still and Christ sends them "into the world" (ei ton kosmon, verse Philippians 18 ), but they must not be like the world nor get their spirit, standards, and message "out of the world," else they can do the world no good. These verses ( Philippians 14-19 ) picture the Master's ideal for believers and go far towards explaining the failure of Christians in winning the world to Christ. Too often the world fails to see the difference or the gain by the change.