I came from the tradition of one Pastor and several Deacons, with the deacons overseeing the church and the pastor serving the practical needs of the fellowship which included the teaching. Of course, there were other staff members as needs grew and they functioned as leaders of volunteers in whatever their area of responsibility.
That was the traditional structure of local churches for the first half century or so of my life in the Southern Baptist Convention. [SBC] And, of course, no divorce permitted for either office. This was just thought to be the system and structure of church-life as it functioned in a local setting. That was a typical Southern Baptist Church as I knew it.
My journey has brought me to a different conviction. I now see in scripture and hold to multiple elders ministering/serving, multiple deacons ministering/serving the congregation with all being servants and the elders being the greatest servants of all. The motive for the ministry of elders/deacons was to equip the congregation [members[ so they can do the work of ministry that is assumed needed in the body through their giftedness and the sharing of the gospel as they went about life.
My reasoning behind this shift of thinking began with an understanding the local "Church." A local church is only a part of the whole Body of Christ with Christ as the Head of the Body. [Head meaning both source and authority.] The whole Church [Body] is to be viewed, as is each local fellowship, as an Organism [living thing] rather than an organization. [structure] And with a study of the words used for pastor, elder, and bishop, as used in scripture, which had not really held much meaning for me personally, up until now, things changed drastically in my understanding. And, boy, was it an eye-opener. Let me show you...
Presbuteros--Elder--was used multiple times in the NT. [Some 40 times]
Episcopos--Bishop--was used multiple times also. [Some 20-30]
Poimea--Pastor--was used ONCE as a noun in the Eph. 4 passage only.
The thing is, it would seem that in scripture all of these words are referring to the same person but from a different functional perspective. Elder refers to people who were older in not just age, but in wisdom and experience as well. Bishop refers to overseeing or having the whole overall picture in mind. And Pastor refers to shepherding or tending to the needs of the sheep.
The kicker was that, in scripture, they are referring to the same person and was always used in the PLURAL with reference to a congregation. When in the context of a congregation, they also, [ except in the KJV where for some reason it ADDS the word "office which is not in the Greek."] were never seen as an office, but had the connotation of ministry or service and THAT without INHERENT authority.
No one is saying that to have one pastor in a congregation is WRONG. I'm just saying it might not be the best. And it may not even be closest to what the scriptures themselves indicate the Holy Spirit gifts the people for as a congregation. But all of this is by implication and understanding of words in their original meaning. No absolute command is given for how the structure is to look.
But whatever structure chosen, Jesus Christ is the Authority, the scriptures are our guide, the Holy Spirit is the One who gifts, and ALL MEMBERS are gifted to serve one another in the body in some fashion and to discern the anointing on those who have different gifts and follow them in their giftedness. We are to be an Organism [One living cell (group) of the Whole Body] when gathered and not just an organization.
That's how the local church is to function whatever the structure.