The "pure in heart" are promised that they will see God face to face and be like him. Purity of heart is the precondition of the vision of God. Even now it enables us to see according to God, to accept others as "neighbors"; it lets us perceive the human body - ours and our neighbor's - as a temple of the Holy Spirit, a manifestation of divine beauty.
Source: Catechism of the Catholic Church (Vatican.va)