He who believes in Christ becomes a son of God. This filial adoption transforms him by giving him the ability to follow the example of Christ. It makes him capable of acting rightly and doing good. In union with his Savior, the disciple attains the perfection of charity which is holiness. Having matured in grace, the moral life blossoms into eternal life in the glory of heaven.
Source: Catechism of the Catholic Church (Vatican.va)