A Centrality of the Church to the Christian is that the Church provides the stronghold of Doctrine and to that, a chain of accountability.
On the day that Israel celebrated the Feast of Weeks (Shavout), some three thousand souls were saved and added to the Church where they continued in the doctrine that the Apostles taught. The Apostles were set above the Church, in as much that Christ was still the head, and this fact was recognized by Paul on several occasions.
And God has appointed these in the church: first apostles, second prophets, third teachers, after that miracles, then gifts of healings, helps, administrations, varieties of tongues.
(1Co 12:28 NKJV)
And He Himself gave some to be apostles, some prophets, some evangelists, and some pastors and teachers, for the equipping of the saints for the work of ministry, for the edifying of the body of Christ, till we all come to the unity of the faith and of the knowledge of the Son of God, to a perfect man, to the measure of the stature of the fullness of Christ; (Eph 4:11-13 NKJV)
When Philip, a deacon, had preached the word in Samaria, the Church at Jerusalem, the most historical see, sent to them Peter and John. We can see that this provides a measure of rigidness, to ensure that new areas did not diverge from the Gospel and the doctrine which was preached in Jerusalem. When a question arose over the Gentiles in the Church and certain laws of the Jews, it was Paul and Barnabbas,that went to Jerusalem and put the question to the Church, where Apostles and Elders (the ministers not Apostles or Deacons – Overseers, etc…) decided the issue. They did not create a new doctrine nor creed, nor formulation, but sought rather to test the question against firmly established doctrine.
And after they (Paul and Barnabbas) had held their peace, James answered, saying, Men and brethren, hearken unto me: Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name. And to this agree the words of the prophets; as it is written, After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up: That the residue of men might seek after the Lord, and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things. Known unto God are all his works from the beginning of the world. Wherefore my sentence is, that we trouble not them, which from among the Gentiles are turned to God: But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood. For Moses of old time hath in every city them that preach him, being read in the synagogues every sabbath day.
(Act 15:13-21 KJVA)
We see that James measure the question against the recent words of the Apostle Simon Peter, and then measured those words (and actions by Peter in the conversion of Cornelius’ house) against the written words of the Prophets (Amos, LXX). Against Peter’s testimony, the actions of God, and the written word of the Prophets, the question was measured and an answer given.
Upon Paul’s conversion and his call to the ministry, he did not turn to himself or to mere men, but before he started his missionary journeys, he went to the Church at Jerusalem to measure his doctrine with that of the Apostles.
To reveal his Son in me, that I might preach him among the heathen; immediately I conferred not with flesh and blood: Neither went I up to Jerusalem to them which were apostles before me; but I went into Arabia, and returned again unto Damascus. Then after three years I went up to Jerusalem to see Peter, and abode with him fifteen days. But other of the apostles saw I none, save James the Lord’s brother.
(Gal 1:16-19 KJVA)
So we see that the Church provides a chain of accountability for ministers of all sorts. They simply cannot branch out on their own, but must be subject to another, whether one to another or to a council or board. The doctrine which they preach must be measured with that of the Church and corrected if need be. (What should be noted is that doctrine must be firm in order for it to provide a measuring line.)
In describing the Church, Paul tells Timothy,
(I)n case I am delayed, to let you know how people ought to conduct themselves in the household of God, because it is the church of the living God, the support and bulwark of the truth.
(1Ti 3:15 NET)
In as such as the Church is the support, or pillar, she is also the stay, keep, bulwark of true, meaning that she is the defense and stronghold of the Doctrine of the Apostles. It is only in the Church which we can find Doctrine and not in Councils, great with mighty and learned men, and nor another place for another god. It is here, the great house of God, that holds and defends the doctrine. From no other source but the Church, should we receive Doctrine.
This is not to dismiss the God-breathed word as second to the Church, as it was the Word of God that formed the Church. The Church is not the creator of Doctrine, but the maintainer and the supporter. To say that the Church is the source of Doctrine is to say that one cannot find right Doctrine from other religions or other secular sources. The very Word of God, the Scriptures, is where we draw the Doctrine from; the Church is what maintains it.
The Centrality of the Church to the Christian is that it is at the Church the doctrine resides, as she alone is the stronghold of the Truth. She supports the Truth and serves as a pillar. And it is her overseers that provide that chain of accountability that traces itself back to the very Apostles.