Most church members have never been told that the singular pastor of a congregation never appears in the New Testament.
And when they had ordained them elders in every church... (Acts 14:23)
And from Miletus he sent to Ephesus, and called the elders of the church. (Acts 20:17)
For this cause left I thee in Crete, that thou shouldest... ordain elders in every city. (Titus 1:5)
To all the saints in Christ Jesus which are at Philippi, with the bishops and deacons. (Philippians 1:1)
The elders which are among you I exhort... Feed the flock of God which is among you. (1 Peter 5:1-2)
Is any sick among you? let him call for the elders of the church. (James 5:14)
Between them, six authors put elders in Jerusalem, Antioch, Lystra, Iconium, Ephesus, Philippi, Crete and the dispersion, always in the plural and in every church. There isn't one verse in which a congregation is led by one man.
The counter-cases, honestly
The three passages usually cited against this deserve a straight answer.
Timothy and Titus. Both are addressed individually and told to appoint elders, but neither is the pastor of a congregation. They are Paul's delegates, sent to a region for a season, with instructions to establish plural leadership and move on. Paul writes for this cause left I thee in Crete (Titus 1:5) and do thy diligence to come unto me (2 Timothy 4:9). Far from being exceptions to the plurality, they're the ones who install it.
The angels of the seven churches (Revelation 2-3). Each letter is addressed to the angel of the church. Some read this as a single bishop. The word is angelos (messenger), used of heavenly beings dozens of times in the same book. The honest thing is to say it's disputed, and a disputed reading is a thin foundation on which to build an office the rest of the New Testament never mentions.
James at Jerusalem. In Acts 15, James speaks last and summarizes. That looks like presiding. But the decision is announced as the decision of the apostles and elders, with the whole church (15:22), and the letter says it seemed good unto us, being assembled with one accord (15:25). James spoke last in a plural body. He didn't decide alone.
And the one man in the New Testament who does run a church alone is Diotrephes, who loveth to have the preeminence (3 John 9). He's presented as a pathology.
Moses could not do it either
The Old Testament's model of single leadership is Moses, and the text records that it didn't work:
And Moses' father in law said unto him, The thing that thou doest is not good. Thou wilt surely wear away, both thou, and this people that is with thee: for this thing is too heavy for thee; thou art not able to perform it thyself alone. (Exodus 18:17-18)
Jethro's diagnosis is structural. When he says the thing that thou doest is not good, he means the arrangement rather than Moses's character. And the remedy is plurality: rulers of thousands, hundreds, fifties, and tens. In Numbers 11, God himself takes of the spirit that was upon him, and gave it unto the seventy elders (11:25). The burden that had sat on a single leader is spread across a body.
If Moses, who spoke with God face to face, couldn't run a single-leader system, the modern pastor isn't going to.
Four reasons plurality is a safeguard
The design's insistence on plurality addresses four documented failure modes of single leadership, none of them administrative.
The first is the information problem. Groups fail to surface information held by only one member; they discuss what everyone already knows and ignore what only one person knows. A single leader has exactly one perspective and no mechanism for hearing the others. Plurality forces the hidden information into the room.
Second comes the dissent problem. A lone dissenter in a group is almost never heard. But the research on conformity found that when a single ally dissents alongside him, conformity collapses. One ally is enough. Plurality is, structurally, Asch's ally made permanent. It guarantees that nobody leading the church is ever the lone voice against a bad decision.
Then there is the manufactured-leader problem. Put a group in a communication structure where everyone must go through one person, and that person becomes the leader regardless of ability. The structure creates the hub. A single-pastor church manufactures the pastor's centrality by routing everything through him, and then mistakes the routing for gifting.
The fourth is the emotional-security problem. Children who witness chronic conflict between the adults responsible for them show measurable loss of emotional security. Although a congregation isn't a family of children, it is a body whose security depends on the stability of its leadership. A single leader's stability is one man's mental health. Plurality distributes the risk.
Peter's instruction to elders names the alternative to all four: neither as being lords over God's heritage, but being ensamples to the flock (1 Peter 5:3). His words are plural, so he has more than one man in view, and he wants examples who can be watched in place of lords.
What plurality does not fix
Honesty requires the other column, since plurality isn't a cure. A plural eldership can conceal collectively as well as a single pastor can conceal alone. Sometimes it does it better, because a group's silence looks like consensus. A board can be captured by one dominant personality and become a rubber stamp. Elders can defer to the senior man and reproduce the single-leader structure under a plural name. Groups can reach worse decisions than individuals when they suppress dissent to preserve harmony. And a plurality that never overrules its most prominent member is a plurality in name only.
Paul and Barnabas were two apostles in a plural leadership, and they had a contention so sharp that they separated (Acts 15:39). Plurality won't prevent conflict. Because there's more than one person to carry the body through it, the conflict becomes visible and survivable.
The salary re-creates the apex
A congregation can fall into a structural trap by appointing five elders and paying one of them. Within a year, the paid one is the pastor and the other four are the board, because presence is authority and the paid one is present all week while the others aren't. The salary re-creates the single leader inside the plural structure.
The design's answer is working elders, men who can say these hands have ministered unto my necessities (Acts 20:34). That way no one elder's presence outweighs the others' by virtue of being the only one there. The elders are equal in office and differentiated in labour.
The overrule test
One test shows whether a congregation has real plurality.
When did the elders last overrule the senior man?
Disagreeing privately doesn't count. To overrule him, the elders have to decide against him, publicly, on something that mattered, and have it stick. If the answer is never, then whatever the structure is called, it's a single-leader church with advisors. Plurality that can't overrule is decoration.
The test cuts the other way too. A senior leader who wants to be overruled has understood what plurality is for. He builds the structure so that he can be overruled, thanks the elder who did it, and treats the overruling as the system working. Where another man would feel a limit on his authority, he finds protection for his people, and for himself, against the one thing no leader can see, his own blind spot.
Whatever the eldership is, the congregation is learning it
Peter called elders ensamples. His word was tupoi, which means patterns, the impression a stamp leaves. Whatever the eldership is, the congregation is learning it. A single leader teaches the congregation that the church is one man's work. A plurality that honours each other, corrects each other, and distributes its labour teaches the congregation what the body is.
Plurality is pedagogy as well as a safeguard against the leader's failure. Every week it gives the congregation a lesson in how a body works. That is the one lesson a single pastor can't teach, however well he preaches it, because the room is watching what he is more than what he says.