We have the craziest clergy system of any Christian denomination. Since The Walk to Emmaus is operated by The Upper Room (a division of GBOD, The UMC), it states a lot of requirements -- particularly as regards clergy credentials -- in keeping with UM practice. Which means none of the other denominations know what to make of the rules. I've tried to explain our clergy system to non-UMs, and all I get is blank stares. Heck, I've tried to explain our clergy system to my parishioners, only to have their eyes glaze over.
Briefly put, there are two classic forms that clergy take in the various Churches. The first is the hierarchical form, which is seen in Catholic, Orthodox, Anglican, (most) Lutheran, and (formerly) Methodist practice. In this, Deacon and Elder (Presbyter, Priest) are successive grades in the ordained ministry of the Church. Most of these denominations also have Bishops; Methodists say that Bishops are Elders consecrated to a particular task, while Catholics and Orthodox say they are a third Order of Ministry. The others trend one way or another.
Reformed Churches, together with many of the newer denominations that came out of the Second Great Awakening -- Presbyterians, UCC, Disciples of Christ, Baptists, etc. -- usually think of Deacon and Elder as lay offices within the local congregation. "Ministers" are ordained as a separate category of persons, though sometimes they are also referred to as Elders -- as in Presbyterian practice, where there are "Ruling Elders" (lay officers) and "Teaching Elders" (clergy).
In the hierarchical Churches, Elders are generally ordained Deacon first, then Elder. In the Reformed Churches, you can be one or the other, and this has nothing to do with being clergy. It was left to United Methodists, beginning in 1996 (the year the Boomers achieved a majority in General Conference) to dispense with tradition and just make up a whole new approach.
We already had a whole bunch of unordained "Local Pastors," clergy by courtesy, so to speak. In 1976, we gave some of them the right to baptize and serve communion. By 1996, they had become, in effect, an Order of the Unordained -- a category of clergy in their own right. No matter how many times you say they have sacramental faculties only when granted by the Bishop, and only in the congregation to which they are appointed, they do not see themselves as provisional clergy. They are just clergy-who-don't-itinerate. They do the ministry of an Elder without the benefit of Elder's orders.
But in '96, we split the diaconate from the presbyterate entirely. Now, you can be ordained an Elder (the pastoral model) or a Deacon (the specialist model), and both are full members of the Annual Conference. Since we no longer associate being ordained Deacon with probationary membership in the Conference, we now have people being "commissioned" Probationary Elders until the time comes for them to be admitted into Full Connection and being ordained.
The whole thing is a mess, and there is zero theological rationale for it. It can't be explained, at least not easily. It can't be defended. It's totally disconnected from any historic sense of identity (tradition), except that it continues to use labels that sound familiar for things that are not. And it doesn't work. Preparation for ordination has become a long death march across burning deserts of earning degrees and piling up debt and dealing with Boards and Committees.
I asked a colleague once if he thought we were getting a better quality of minister by all that we make candidates go through. He replied, we do this because we find it difficult to say No, as in "We love you, but we won't ordain you." Instead, we create a harrowing obstacle course in order to discourage people, so they'll drop out instead of having to be dropped by us. What we get at the end are survivors, not servant-leaders: clergy who know how to keep going in spite of all pain and weariness and the clash of ideologies; clergy who mouth the appropriate slogans and don't care what they mean by them, so long as they make it to the next level. It's crazy, and it's irresponsible.
If I could work my will, I would restrict the administration of the sacraments to clergy: to Deacons under the supervision of an Elder, and to Elders in their own right. But I would then ordain as Elder all those whom we admit have a lifetime call to the pastoral ministry. I would make the Course of Study equivalent to a seminary degree (as it was, historically, in Methodism), and I would beef up the Course of Study. If you wanna join the club, you can go to seminary or do the Course of Study. Your choice. Bi-vocational pastors, etc., could be ordained Elder upon completion of the Course of Study. They could refuse to itinerate by accepting what we call Honorable Location, which restricts their sacramental rights to the charge in which they hold membership.
To minister to the small churches which are too small to have a full-time pastor, I would use retired Elders, and I would tell serving Elders they should expect to be the senior pastor of multiple churches in many cases (with Local Pastor and Certified Lay Speaker help). Being an Elder means surrendering yourself to do the work; it is not a union card that says the good, easy, high-paying jobs are reserved for me.
The diaconate should be the stepping stone to the presbyterate, as it is historically. The difference, is, I would open Deacon's Orders to those who do not have the full boat of clergy credentials -- the specialists. Specialists (youth workers, Christian educators, music ministers, etc.) would be permanent Deacons and Associate Members of Annual Conference. Those on track for serving as traditional clergy would be Probationary Members and go to be ordained Elder at the time of their being received as Full Members of the Annual Conference.