The authority of the church, though, is in the authority of the Word of God. There is real power in the reading and preaching of God’s Word, and there is real power in the administration of the sacraments. When we declare God’s Word by reading it, and when we minister God’s Word through preaching and the sacraments, King Jesus exercises His authority over His church.
As a fundamental principle of church government in the Presbyterian Church in America (PCA), our Book of Church Order limits church power and authority to be only ministerial and declarative:
All church power, whether exercised by the body in general, or by representation, is only ministerial and declarative since the Holy Scriptures are the only rule of faith and practice. No church judicatory may make laws to bind the conscience. All church courts may err through human frailty, yet it rests upon them to uphold the laws of Scripture though this obligation be lodged with fallible men.
Preliminary Principle 7 (emphasis mine)
This is perhaps the most important principle for developing a thoroughly biblical ecclesiology (doctrine of the church). Understanding church power as only ministerial and declarative helps to navigate several thorny theological and practical issues of church government.
Church Power is Not Magisterial and Legislative
By affirming what church power is, we are also denying what church power is not. Specifically, we are denying the doctrine of the Roman Catholic Church that church power is magisterial and legislative. In Roman Catholicism, the Church (i.e., the Roman Catholic Church alone) holds the authority to establish dogma. The idea is that Jesus Christ has invested the church with a deposit of tradition that stands alongside the deposit of Scripture.
Protestants, on the other hand, believe that the church is entirely under the authority of the Scriptures. Since God speaks through his Word and Spirit alone, we must constantly reform our faith and practice by nothing but the Bible.
Therefore, the established doctrine of the Roman Catholic Church is that the Church itself (through a hierarchical Magisterium) holds two powers that Protestants reserve for God alone, speaking in and through His Word and by His Spirit.
Infallible Interpretations of Scripture
First, the official position of the Roman Catholic Church is that the Magisterium (i.e., the teaching authority of the Pope and the Bishops of the Church) includes the power to declare infallible interpretations of the Scripture.
Protestants affirm with Scripture that the church is “a pillar and buttress of the truth” (1 Tim. 3:15). But, we believe that the Scriptures (i.e., the 66 canonical books of the Bible) themselves are infallible, not our interpretations of the Scriptures. Here is what the Westminster Confession of Faith teaches:
The supreme judge by which all controversies of religion are to be determined, and all decrees of councils, opinions of ancient writers, doctrines of men, and private spirits, are to be examined, and in whose sentence we are to rest, can be no other but the Holy Spirit speaking in the Scripture.
WCF 1.10
All synods or councils, since the Apostles’ times, whether general or particular, may err; and many have erred. Therefore they are not to be made the rule of faith, or practice; but to be used as a help in both.
WCF 31.3
We must submit even our confessional documents to the authority of Scripture. That is, we hold to our confessional statements only because we believe that they accurately expound the Scriptures. If our Creeds and Confessions teach something different from the Scriptures, we must obey the Scriptures. Only the Scriptures (and not our Creeds and Confessions) are the rule of faith.