Holiness is not wholeness as the world understands it but faithfulness, perseverance in obedience. It means wholehearted dedication to the living God through service in his name. To aspire to holiness is to aspire to something other than a virtuous life or even a fulfilled life. What makes the holy person distinctive is not so much adherence to conventional moral standards as consecration to the Wholly Other, who stands in judgment over all human values and aspirations. Holiness excludes not only immorality but also mediocrity. It involves not only obedience to the law but also zeal for the faith.
The Christian life is characterized by passive sanctity and active holiness. The Holy Spirit secretly works sanctity within us; our task is to manifest this work of the Spirit in our everyday activities. We do not procure sanctity or holiness, but we can do works that reveal the holiness of Christ. We do not earn holiness, but we can demonstrate, celebrate and proclaim his holiness.
~Donald Bloesch, God the Almighty: Power, Wisdom, Holiness, Love, pg. 159.