No wonder that Paul, in the chapter in which he has spoken to the Ephesians of their being ‘chosen to be holy,’ prays for the spirit of wisdom and revelation in the knowledge of God to be given to believers, that they might know ‘the hope of their calling’ (i. 17, 18). Let all of us, who feel that we have too little realized that we are called to Holiness, pray this prayer. It is just what we need. Let us ask God to show us how, as He who hath called us is Himself holy, so we are to be holy too; our calling is a holy calling a calling before and above everything, to Holiness. Let us ask Him to show us what Holiness is, His Holiness first, and then our Holiness; to show us how He has set His heart upon it as the one thing He wants to see in us, as being His own image and likeness; to show us too the unutterable blessedness and glory of sharing with Christ in His Holiness. Oh! that God by His Spirit would teach us what it means that we are called to be holy as He is holy. We can easily conceive what a mighty influence it would exert.
From Holy in Christ by Andrew Murray