CCC 940
Profession of Faith›SECTION TWO I. THE CREEDS›CHAPTER THREE I BELIEVE IN THE HOLY SPIRIT›Paragraph 4. CHRIST'S FAITHFUL - HIERARCHY, LAITY, CONSECRATED LIFE
"The characteristic of the lay state being a life led in the midst of the world and of secular affairs, lay people are called by God to make of their apostolate, through the vigor of their Christian spirit, a leaven in the world" (AA 2 # 2).