40 The Lord Jesus, the divine Teacher and Model of all perfection, preached holiness of life to each and everyone of His disciples of every condition. He Himself stands as the author and consumator of this holiness of life: "Be you therefore perfect, even as your heavenly Father is perfect".(216) Indeed He sent the Holy Spirit upon all men that He might move them inwardly to love God with their whole heart and their whole soul, with all their mind and all their strength and that they might love each other as Christ loves them. The followers of Christ are called by God, not because of their works, but according to His own purpose and grace. They are justified in the Lord Jesus, because in the baptism of faith they truly become sons of God and sharers in the divine nature. In this way they are really made holy. Then too, by God's gift, they must hold on to and complete in their lives this holiness they have received. They are warned by the Apostle to live "as becomes saints", and to put on "as God's chosen ones, holy and beloved a heart of mercy, kindness, humility, meekness, patience", and to possess the fruit of the Spirit in holiness. Since truly we all offend in many things we all need God's mercies continually and we all must daily pray: "Forgive us our debts"(223) Thus it is evident to everyone, that all the faithful of Christ of whatever rank or status, are called to the fullness of the Christian life and to the perfection of charity; by this holiness as such a more human manner of living is promoted in this earthly society. In order that the faithful may reach this perfection, they must use their strength accordingly as they have received it, as a gift from Christ. They must follow in His footsteps and conform themselves to His image seeking the will of the Father in all things. They must devote themselves with all their being to the glory of God and the service of their neighbor. In this way, the holiness of the People of God will grow into an abundant harvest of good, as is admirably shown by the life of so many saints in Church history.
Source: Lumen Gentium (Vatican.va)