Also in reaction against the Donatists, Augustine developed a distinction between the "regularity" and "validity" of the sacraments.
Regular sacraments are performed by clergy of the Catholic Church, while sacraments performed by schismatics are considered irregular.
Nevertheless, the validity of the sacraments do not depend upon the holiness of the priests who perform them (ex opere operato); therefore, irregular sacraments are still accepted as valid provided they are done in the name of Christ and in the manner prescribed by the Church.
On this point Augustine departs from the earlier teaching of Cyprian, who taught that converts from schismatic movements must be re-baptised.
Augustine taught that sacraments administered outside the Catholic Church, though true sacraments, avail nothing.
However, he also stated that baptism, while it does not confer any grace when done outside the Church, does confer grace as soon as one is received into the Catholic Church.

Augustine upheld the early Christian understanding of the real presence of Christ in the Eucharist, saying that Christ's statement, "This is my body" referred to the bread he carried in his hands, and that Christians must have faith the bread and wine are in fact the body and blood of Christ, despite what they see with their eyes.
For instance he stated that "He [Jesus] walked here in the same flesh, and gave us the same flesh to be eaten unto salvation.
But no one eats that flesh unless first he adores it; and thus it is discovered how such a footstool of the Lord's feet is adored; and not only do we not sin by adoring, we do sin by not adoring."

Nevertheless, in some of his writings, Augustine expressed a symbolic view of the Eucharist.
For example, in his work On Christian Doctrine, Augustine referred to the Eucharist as a "figure" and a "sign."

Against the Pelagians, Augustine strongly stressed the importance of infant baptism.
About the question whether baptism is an absolute necessity for salvation, however, Augustine appears to have refined his beliefs during his lifetime, causing some confusion among later theologians about his position.
He said in one of his sermons that only the baptized are saved.
This belief was shared by many early Christians.
However, a passage from his City of God, concerning the Apocalypse, may indicate Augustine did believe in an exception for children born to Christian parents.
Also in reaction against the Donatists, Augustine developed a distinction between the "regularity" and "validity" of the sacraments. Regular sacraments are performed by clergy of the Catholic Church, while sacraments performed by schismatics are considered irregular. Nevertheless, the validity of the sacraments do not depend upon the holiness of the priests who perform them (ex opere operato); therefore, irregular sacraments are still accepted as valid provided they are done in the name of Christ and in the manner prescribed by the Church. On this point Augustine departs from the earlier teaching of Cyprian, who taught that converts from schismatic movements must be re-baptised. Augustine taught that sacraments administered outside the Catholic Church, though true sacraments, avail nothing. However, he also stated that baptism, while it does not confer any grace when done outside the Church, does confer grace as soon as one is received into the Catholic Church.
Augustine upheld the early Christian understanding of the real presence of Christ in the Eucharist, saying that Christ's statement, "This is my body" referred to the bread he carried in his hands, and that Christians must have faith the bread and wine are in fact the body and blood of Christ, despite what they see with their eyes. For instance he stated that "He [Jesus] walked here in the same flesh, and gave us the same flesh to be eaten unto salvation. But no one eats that flesh unless first he adores it; and thus it is discovered how such a footstool of the Lord's feet is adored; and not only do we not sin by adoring, we do sin by not adoring."
Nevertheless, in some of his writings, Augustine expressed a symbolic view of the Eucharist. For example, in his work On Christian Doctrine, Augustine referred to the Eucharist as a "figure" and a "sign."
Against the Pelagians, Augustine strongly stressed the importance of infant baptism. About the question whether baptism is an absolute necessity for salvation, however, Augustine appears to have refined his beliefs during his lifetime, causing some confusion among later theologians about his position. He said in one of his sermons that only the baptized are saved. This belief was shared by many early Christians. However, a passage from his City of God, concerning the Apocalypse, may indicate Augustine did believe in an exception for children born to Christian parents.
Augustine of Hippo