Though i have not seen this verse infallibly defined, RCAs lay much weight upon this verse in contending this refers to Rome being the assuredly infallible instrumental source of and authority on truth, even though (or because) the text only says "church of the living God, the pillar and ground of the truth," in which the words rendered "pillar and ground" (DRB) or "pillar and foundation" (NAB) - "stulos" and "hedraiōma" - both denote support(ing). The former is used as "pillar" elsewhere while latter only occurs here in Scripture, and while it comes from a word which can mean support in the sense of ground, is not one of the words used for foundation, (katabolē, themelios) collectively 22 times, and which Christ is said to be. (Some believe the pillar and ground in this verse refer to the living God.) The word of "of the" (truth) is only one word, and can be rendered "to the" (Mt. 5:25) but here "of the" would seem to be required.
Vines states "Στύλος pillar, in Paul only Gal_2:9. In Rev_3:12; Rev_10:1. Ἑδραίωμα stay, prop, better than ground. N.T.o. olxx, oClass. The kindred adjective ἑδαῖος firm, stable, 1Co_7:37; 1Co_15:58; Col_1:23. These words are in apposition with church.
The idea is that the church is the pillar, and, as such, the prop or support of the truth. It is quite beside the mark to press the architectural metaphor into detail. By giving to ἑδραίωμα the sense of stay or prop, the use of the two words for the same general idea is readily explained. The church is the pillar of the truth, and the function of the pillar is to support."
And again, that "the church of the living God, the pillar and ground of the truth," refers to the church being just that finds no objection with us under SS, for the church upholds the truth, the Scriptures being the assured word of truth, while the church is also "of the truth" in being built upon truth, principally the truth of Peter's Scriptural confession, and thus Christ Himself, "On the rock of this faith confessed by St Peter, Christ build his Church,” (CCC, pt. 1, sec. 2, cp. 2, para. 424).
The upholds this truth most primarily by preaching "the word of the truth of the gospel," (Col. 1:5) which "now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith: " (Romans 16:26)
But using this verse to uniquely refer to the Roman Catholic Church and its assuredly infallible magisterium (AIM) under its petrine papacy, perpetuated thru apostolic succession - all of which it must according to their private interpretation of it - requires
a level of extrapolation which relates to and is akin to the attempts to force Mt. 16:18 and other texts to refer to the same, which they will not do individually or collectively, nor is premise that a perpetual AIM is necessary to preserve Truth Scriptural.
As said, unto the Israelites "were committed the oracles of God" (Rm. 3:2) and "to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises; Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen. " (Romans 9:4-5)
Yet Scripture was given and established, and truth was preserved without an assuredly infallible perpetual magisterium of men, but the Scriptures were established as the perpetual assured word of God, and standard for obedience and testing truth claims, and so it is today.
Agreed! The truth that the church is supposed to support and uphold MUST be the same truth that was recorded in Holy Scripture - which is the only divinely-inspired and assuredly infallible authority that has been given to us by God. I read elsewhere, though I can't recall where, that the "pillar" used in the I Timothy passage can also be tied to the pillar of fire by night and of cloud by day that the Lord God used to guide the children of Israel out of Egypt. It is the sure guidepost of God himself that leads us into all truth. Without it, we would wander aimlessly never knowing for certain if what we believe is correct. That is how the church is supposed to be used by God - to lead people to the truth. When anyone - or organization - ceases to be the true guide leading to the truth found in God's word, then they cease being the buttress and support of truth. They stop being what God wants them to be and those who follow them will find they have been led into a ditch rather than the straight and narrow path that leads to eternal life and those who mislead bring sure judgment and condemnation upon themselves.