The sixth beatitude proclaims, "Blessed are the pure in heart, for they shall see God." "Pure in heart" refers to those who have attuned their intellects and wills to the demands of God's holiness, chiefly in three areas: charity; chastity or sexual rectitude; love of truth and orthodoxy of faith. There is a connection between purity of heart, of body, and of faith:
The faithful must believe the articles of the Creed "so that by believing they may obey God, by obeying may live well, by living well may purify their hearts, and with pure hearts may understand what they believe."
Source: Catechism of the Catholic Church (Vatican.va)