Catholic theology
Catholic belief holds that the church exists both on earth and in heaven simultaneously, and thus the Virgin Mary and the saints are alive and part of the living church. Prayers and devotions to Mary and the saints are common practices in Catholic life. These devotions are not worship, since only God is worshiped. The church teaches that the saints "do not cease to intercede with the Father for us. ... So by their fraternal concern is our weakness greatly helped."
Catholic Church
According to church doctrine, the sacraments of the church require the proper form, matter, and intent to be validly celebrated. In addition, the Canon Laws for both the Latin Church and the Eastern Catholic Churches govern who may licitly celebrate certain sacraments, as well as strict rules about who may receive the sacraments. Notably, because the church teaches that Christ is present in the Eucharist, those who are conscious of being in a state of mortal sin are forbidden to receive the sacrament until they have received absolution through the sacrament of Reconciliation (Penance). Catholics are normally obliged to abstain from eating for at least an hour before receiving the sacrament. Non-Catholics are ordinarily prohibited from receiving the Eucharist as well.