Although among heretics and schismatics there is the same Baptism, nevertheless, the remission of sins is not operative among them because of the very rottenness of discord and wickedness of dissension ... Baptism was in them, but it did not profit them outside the Church ... Outside the Church, Baptism works death because of discord.
Saint AugustineWhat the universal Church holds, not as instituted [invented] by councils but as something always held, is most correctly believed to have been handed down by apostolic authority. Since others respond for children, so that the celebration of the sacrament may be complete for them, it is certainly availing to them for their consecration, because they themselves are not able to respond.
Saint Augustine