Holiness that flows from the Heart

Just as he who called you is holy, 

so be holy in all you do,

for it is written:

"Be holy, because I am holy.''

1 Peter 1.15,16

I found Edmund Clowney's (from his BST commentary on 1 Peter) description of what it means to be holy really helpful:

We are to be imitators of God as beloved children; holy as he is holy, perfect as our Father in heaven is perfect. The pattern of holy living cannot be reduced to a limited number of 'holy' actions. God's righteous deeds flow from his holy nature; holiness patterned on his must express transformed hearts. On the one hand, this seems to set an impossible standard: how can we be like the holy God? On the other hand, there is a marvellous simplicity in a holiness patterned on God himself: it does not require encyclopedic grasp of endless directives and prohibitions. It flows from the heart; its key is love. To be holy is to love the Lord our God with heart, soul, strength and mind, and to love our neighbour as ourselves. We imitate the love of grace that saved us, the love of God's compassion poured out in our hearts by the Holy Spirit.