(b) Practically, this opinion is safer, and hence all theologians, even Probabilists, hold that one must act as if it were true and certain, whenever it is possible to give instruction on the Trinity and Incarnation.
790. Knowledge about the mysteries of faith is either substantial (by which one knows the essentials of a mystery) or scientific (by which one knows also its circumstances and details, and is able to give a more profound explanation of it). Scientific knowledge is required, on account of their office, in those who are bound to teach the faith, but substantial knowledge suffices for salvation. Hence, for an adult to be saved, it suffices that he have the following kind of knowledge about the four great mysteries:
(a) There is a God who has spoken to us, promising freely that He will take us to Himself as our reward. It is not necessary that one understand such theological concepts as the essence of deity, the definition of supernaturality, the formal and material objects of beatitude, etc.; for many persons are incapable of understanding them.
(b) This God, who will be our reward, is one, but there are three divine Persons—the Father, the Son and the Holy Ghost, really distinct and equal. It is not necessary that one understand the distinction between nature and person, nor subtle questions about the processions and properties.
(c) God provides for us, giving us the helps we need, and also, if we serve Him, the reward He has promised. It is not necessary that one understand the theology of providence, grace, and merit.
(d) Jesus Christ, who is God the Son, became man, suffered and died for us, thus saving us from sin and winning back for us the right to heaven. It is not necessary that one understand scientifically that in Christ there are two natures united hypostatically in the one Person of the Word.
791. Since Baptism is fruitless without due faith in the recipient, it is not lawful as a rule to baptize those who lack substantial knowledge of the four mysteries just mentioned. (a) Outside of danger of death, it is never lawful to baptize a person, adult in mind, who is in substantial ignorance of any of these four mysteries. Such a person must first receive instruction. (b) In danger of death, when instruction cannot be given, an adult in substantial ignorance about the Trinity and the Incarnation may be baptized conditionally; for it is probable that explicit knowledge of those two mysteries is not a necessity of means (see 789; Canon 752, Sec.2).
792. Since absolution is invalid if the person absolved is incapable of receiving grace, and since acts of faith in the four chief mysteries are an essential means to justification in adults, absolution given to one who is in substantial ignorance about one of the four mysteries above mentioned is certainly or probably invalid, as the case may be. Absolution certainly invalid is never lawful, but absolution probably valid may in certain cases be regarded as lawful before administration, and as valid after administration. Hence, the following cases must be distinguished:
(a) Outside of danger of death, it is not lawful to absolve one who is in substantial ignorance about any of those four mysteries. Such a person should be sent away for further instruction, or given a brief instruction then and there, if there is time.
(b) In danger of death, when instruction cannot be given, an adult in substantial ignorance about the Trinity and Incarnation may be absolved conditionally, for the reason given in the similar case of Baptism.