Some considerations and implications from the New Testament examples
Matthew 18:15-18 - Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican. Verily I say unto you, Whatsoever ye shall bind on earth shall be bound in heaven: and whatsoever ye shall loose on earth shall be loosed in heaven.
In the matter of consensus concerning fellowship, the matter (if unresolved at the person to person level) is taken to the church/ekklesia/assembly.
Acts 1:15,21-26 - And in those days Peter stood up in the midst of the disciples, and said , (the number of names together were about an hundred and twenty,) ...Wherefore of these men which have companied with us all the time that the Lord Jesus went in and out among us, Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection. And they appointed two, Joseph called Barsabas, who was surnamed Justus, and Matthias. And they prayed, and said, Thou, Lord, which knowest the hearts of all men, shew whether of these two thou hast chosen, That he may take part of this ministry and apostleship, from which Judas by transgression fell, that he might go to his own place. And they gave forth their lots; and the lot fell upon Matthias; and he was numbered with the eleven apostles.
In this account of unified decision making in the church, the they are some 120 men and women uniting together concerning the matter of Matthias.
Acts 6:1-5 - And in those days, when the number of the disciples was multiplied, there arose a murmuring of the Grecians against the Hebrews, because their widows were neglected in the daily ministration. Then the twelve called the multitude of the disciples unto them, and said, It is not reason that we should leave the word of God, and serve tables. Wherefore, brethren, look ye out among you seven men of honest report, full of the Holy Ghost and wisdom, whom we may appoint over this business. But we will give ourselves continually to prayer, and to the ministry of the word. And the saying pleased the whole multitude: and they chose Stephen, a man full of faith and of the Holy Ghost, and Philip, and Prochorus, and Nicanor, and Timon, and Parmenas, and Nicolas a proselyte of Antioch:
Again in this case it is the they, the whole multitude of disciples/the whole church, that chose the seven.
Acts 13:1-3 - Now there were in the church that was at Antioch certain prophets and teachers; as Barnabas, and Simeon that was called Niger, and Lucius of Cyrene, and Manaen, which had been brought up with Herod the tetrarch, and Saul. As they ministered to the Lord, and fasted, the Holy Ghost said, Separate me Barnabas and Saul for the work whereunto I have called them. And when they had fasted and prayed, and laid their hands on them, they sent them away.
The church at Antioch is unified in sending Paul and Barnabas. They receive the message of the Holy Spirit and act upon it.
Acts 15:1-3 - And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved. When therefore Paul and Barnabas had no small dissension and disputation with them, they determined that Paul and Barnabas, and certain other of them, should go up to Jerusalem unto the apostles and elders about this question. And being brought on their way by the church, they passed through Phenice and Samaria, declaring the conversion of the Gentiles: and they caused great joy unto all the brethren.
Though disagreeing over circumcision, the Antioch church apparently reached a consensus agreement to send Paul and Barnabas to Jerusalem concerning the problem.
Acts 15:22-23 - Then pleased it the apostles and elders, with the whole church, to send chosen men of their own company to Antioch with Paul and Barnabas; namely, Judas surnamed Barsabas, and Silas, chief men among the brethren: And they wrote letters by them after this manner; The apostles and elders and brethren send greeting unto the brethren which are of the Gentiles in Antioch and Syria and Cilicia:
The "apostles and elders, with the whole church" at Jerusalem came to a united decision on the circumcision question before them and send Paul, Barnabas and others with a letter of clarification.
I Corinthians 5 & 6 - The whole church were to unitedly carry out the fellowship and discipline of the church, and in weighty matters, even the "least esteemed" are competent to judge.
I Cor. 14:23,27-31 - If therefore the whole church be come together into one place, ...If any man speak in an unknown tongue, let it be by two, or at the most by three, and that by course; and let one interpret. But if there be no interpreter, let him keep silence in the church; and let him speak to himself, and to God. Let the prophets speak two or three, and let the other judge. If any thing be revealed to another that sitteth by, let the first hold his peace. For ye may all prophesy one by one, that all may learn, and all may be comforted.
When the whole church came together at Corinth, among other things, they were to judge that which was prophesied.
II Thess. 3:6-15 - Now we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us. For yourselves know how ye ought to follow us: for we behaved not ourselves disorderly among you; Neither did we eat any man's bread for nought; but wrought with labour and travail night and day, that we might not be chargeable to any of you: Not because we have not power, but to make ourselves an ensample unto you to follow us. For even when we were with you, this we commanded you, that if any would not work, neither should he eat. For we hear that there are some which walk among you disorderly, working not at all, but are busybodies. Now them that are such we command and exhort by our Lord Jesus Christ, that with quietness they work, and eat their own bread. But ye, brethren, be not weary in well doing. And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed. Yet count him not as an enemy, but admonish him as a brother.
The church must act in unison to carry out these commands of the apostle.
Although the whole church was not represented, Peter asked consensus of the disciples who traveled with him to Cornelius' household (Acts 10:47) concerning the baptism of these Gentiles. This shows deference to and interest in the opinion/spiritual discernment of others, and was not very pope-like.
These New Testament examples seem to have a common thread running through them. Even in cases of a direct command from the Lord through an apostle, the church had to act in a unified manner to carry it out. It is not a complicated matter that requires years of the study of parlimentary procedure in order to know how to conduct business, but the simplicity of finding out what the Lord wants and acting in concert.
The unified decision-making carried out by the church does not imply no leadership in the church. The entire church body is led both by the Holy Spirit and the elders whom the Spirit has placed among them. Ultimately the "decision-making" is judicial -- judging or understanding what the Lord says do and then doing it -- but "the whole church" is involved.