Church, though I don’t doubt that their is a physicalness to it, in that it is called the “body” of Christ, it certainly is much more than JUST the church at Rome… Here for starter is what some ECF’s had to say about the “church” being something other than or more than the Roman church.
"Moreover, after the pledging both of the attestation of faith and the promise of salvation under ‘three witnesses,’ there is added, of necessity, mention of the Church; inasmuch as, wherever there are three, (that is, the Father, the Son, and the Holy Spirit) there is the Church, which is a body of three." - Tertullian (On Baptism, 6)
Roman Catholics tell us that the church is a worldwide denomination led by a Pope, an institution whose legitimacy doesn’t depend on moral character. But Lactantius tells us:
"In the next place, Solomon was never called the son of God, but the son of David; and the house which he built was not firmly established, as the Church, which is the true temple of God, which does not consist of walls, but of the heart and faith of the men who believe on Him, and are called faithful…
(The Divine Institutes, 4:13,
Catholic apologists often claim that nobody in the early centuries of Christianity referred to the church as a spiritual entity consisting only of believers. The truth is that, although other definitions were advocated as well, the idea of a spiritual entity consisting only of believers was one of the definitions. For example:
“Moreover, that the word of God speaks to those who believe in Him as being one soul, and one synagogue, and one church, as to a daughter; that it thus addresses the church which has sprung from His name and partakes of His name (for we are all called Christians), is distinctly proclaimed in like manner in the following words, which teach us also to forget our old ancestral customs, when they speak thus: ‘Hearken, O daughter, and behold, and incline thine ear; forget thy people and the house of thy father, and the King shall desire thy beauty: because He is thy Lord, and thou shalt worship Him.’” - Justin Martyr (Dialogue with Trypho, 63)
Clement of Alexandria
Roman Catholic apologists sometimes deny that anybody defined the Christian church as a spiritual entity consisting only of believers during the earliest centuries of Christianity. The truth is that the term “church” was defined in numerous ways, and the concept of an invisible church was one of those definitions. In an earlier segment in this series, I cited Justin Martyr as an example. Here’s Clement of Alexandria:
“For it is not now the place, but the assemblage of the elect, that I call the Church.” (The Stromata, 7:5)
I’ll let you all get started with these and since you’d expect a protestant to use scripture i’ll hold off on that.