because He shall abide with you, and shall be in you” (14:16, 17). “These things have I spoken to you, abiding with you. But the Paraclete, the Holy Ghost, Whom the Father will send in My name, He will teach you all things, and bring all things into your mind, whatsoever I shall have said to you” (ibid., 25, 26). “But when the Paraclete cometh, Whom I will send you from the Father, the Spirit of truth, Who proceedeth from the Father, He shall give testimony of Me: and you shall give testimony, because you are with Me from the beginning” (15:26, 27). “When He, the Spirit of truth, is come, He will teach [ὁδογήσει] you all truth” (16:13). It is plain that these promises were made to the Apostles as future propagators of the Faith, and the stress laid upon the functions of the Holy Ghost as the Spirit of truth, as Teacher and Witness, as Keeper of and Guide to the truth, is intended to show that the transmission of Revelation was to be endowed with all the qualifications required for its object, and especially with infallibility. Lastly, the Pastor appointed by Christ (John 21:15–17) had been previously designated as being strengthened in Faith in order to confirm his brethren, and as the rock which was to be the indestructible foundation of the Church (Luke 22:31, 32; Matt. 16:18).
These passages taken together may be summarized as follows. After accomplishing His own mission, Jesus Christ, in virtue of His absolute power and authority, sent into the world a body of teachers and preachers, presided over by one Head. They were His representatives, and had for their mission to publish to the world all revealed truth until the end of time. Their mission was not exclusively personal—it was to extend to their successors. Mankind were bound to receive them as Christ Himself. That their word might be His word, and might be recognized as such, He promised them His presence and the aid of the Holy Ghost to guarantee the infallibility of their doctrine; He promised external and supernatural signs as vouchers for its authenticity; finally, He gave their doctrine an effective sanction by holding out an eternal reward to those who should faithfully adhere to it, and by threatening with eternal punishment those who should reject it.
