(a) To the Gift of Understanding corresponds the Sixth Beatitude: “Blessed are the pure of heart, for they shall see God.” For by Understanding the mind is pure from wrong ideas of truth, and sees that God is above all that the intellect can comprehend. The two fruits that proceed from Understanding are faith (i.e., conviction about revealed truth) and ultimately joy, in union with God through charity. (b) To the Gift of Knowledge corresponds the Third Beatitude: “Blessed are they that mourn, for they shall be comforted.” For by Knowledge one judges rightly about created things, grieves over the wrong use made of them, and is comforted when they are turned to their proper end. Art. 2: THE SINS AGAINST FAITH (_Summa Theologica_, II-II, qq. 10-15.) 812. The sins against faith can all be reduced to four heads: (a) sins of unbelief (see 813-886), which are opposed to the internal act of faith; (b) sins of blasphemy (see 887-903), which are opposed to the external act of faith; (c) sins of ignorance (see 904-911), which are opposed to the Gift of Knowledge; (d) sins of blindness and dullness (912), which are opposed to the Gift of Understanding. 813. The Sin of Unbelief.--Unbelief in general is a want of faith. It is of two kinds, negative and positive. (a) Negative unbelief is the absence of faith in a person who has never heard of it at all, or only insufficiently. Thus, the Indians in America before the coming of Christian missionaries were negative unbelievers. This kind of unbelief is a punishment, since it results from original sin; but it is not a sin itself, and those who die in negative unbelief are lost, not on account of this, but on account of sins against the natural law (John, xv. 22; Rom., x. 14). With this kind of unbelief we are not here concerned. (b) Positive unbelief is the absence of faith in one who has heard it sufficiently, so that the lack of it is due to his own fault. This kind of unbelief is, of course, a sin, for it supposes that one is acting against the light one has received. 814. Positive unbelief is either a refusal or a renouncement of faith. (a) Ordinary unbelief is a refusal of faith, that is, non-acceptance of faith by one who has never had faith; (b) apostasy, or desertion, is the abandonment of faith by one who formerly accepted it. This is not a distinct kind of unbelief, since, like ordinary unbelief, it has for its object or term the denial of revealed truth; but it is an aggravating circumstance of unbelief (II Peter, ii. 21). 815. The sin of unbelief is, committed either directly or indirectly. (a) It is committed directly, when one rejects what pertains to faith (its acts, objects or motive); (b) it is committed indirectly, when one guiltily places oneself or others in the occasion or danger of unbelief. The dangers against faith will be considered after the sins of unbelief (see 848-886).