To understand Calvin's Institutes one must understand what he means by piety. From book 1, chapter 2, I call "piety" that reverence joined with with love of God which the knowledge of his benefits induces. For until men recognize that they owe everything to God, that they are nourished by his fatherly care, that he is the Author of their every good, that they should seek nothing beyond him - they will never yield him willing service. Nay, unless they establish their complete happiness in him, they will never give themselves truly and sincerely to him.
Calvin: Institutes of the Christian Religion (2 Volume Set)