The conclusion that the sacraments are effective “ex opere operato” (from the work worked) was one of the results of the Church’s dealing with the Donatists.

Caecilian noted that  "the validity of the sacraments and of other such acts cannot be made to depend on the worthiness of the one administering them, for in that case all Christians would be in constant doubt regarding the validity of their own baptism or of the communion of which they had partaken."

The Church concluded that the efficacy of the sacrament is a result, not of the holiness of a priest or minister, but rather of Christ Himself who is the Author of each sacrament. The priest or minister acts in persona Christi (in the person of Christ), even if in a state of mortal sin.

The principle affirms that while a proper disposition is necessary to exercise the efficacious grace in the sacraments, it is not the cause of the sufficient grace.