Expert: Griff Ruby - 2/20/2007

Question
what are the three ministries of holy orders?

Answer
By "ministries" I am assuming that you mean the degrees of the Sacrament of Holy Orders.
Actually, there are eight such degrees of Holy Orders, but five of them have largely fallen into disuse.  Each degree conveys the authority and "power" to do what that degree stands for, in ascending order.  Some things would seem like things a person could just do without any need of Holy Orders, and in fact many of these things do get done by unordained persons these days.  But there is doing something in one's own power and there is doing something with the Grace of God specifically to do it.  To illustrate, two persons could set up housekeeping together and probably make a practical go of it, but should the going get rough, there is no good reason for one or the other to bow out and no mystical tie between them to empower them to overcome the difficulties.  But with the Sacrament of matrimony, a man and a woman can be empowered to be bound to each other in a mystical manner that they can never break, and which provides them with the graces and power to get through the rough times and still come out together as a unit.
Likewise, each degree of Holy Orders so empowers and provides the specific Graces to do a job appropriate to the degree conferred.
The eight (original) degrees to Holy Orders are:
1)  Porter - qualified to guard the door, ring the bell, be responsible for the physical plant of the Church building.
2)  Lector - qualified and authorized to hold the sacred Liturgical books, and to read the Epistles and Psalms therefrom.
3)  Exorcist - qualified to perform minor blessings on objects and places, (NOT to be confused with an "Exorcist" who drives out demons as in the movie, that requires a full fledged priest (or bishop) with much in the way of specific training and further spiritual qualifications).
4)  Acolyte - qualified to serve at the altar, handle the sacred vessels, and in short do all the things an Altar boy does (it has been a long-accepted dispensation that many who serve as Altar boys do not have any degree of Holy Orders, but ideally and strictly speaking, Altar boys should be such "priests-in-training" who have attained at least this rank of Holy Orders).
5)  Subdeacon - authorized and empowered to assist the priest in more advanced degrees, also serves to assist the deacons in whatever way.  Classically, it would be upon attainment of this degree of Holy Orders that one would take their vow of celibacy.
These first five degrees are the ones that are seldom seen these days (but they do still exist, albeit only in traditional circles).
6)  Deacon - originally created (in the Bible) to "wait on tables" (feeding the poor and such practical works) so that the Apostles would not have to do this, deacons assist the Priest in many such practical manners, and also are entitled to perform many parts of the Mass, including reading the Gospel, giving the Homily, and many of the other prayers.  The key prayer is reserved to the next degree of Holy Orders, the priesthood.
7)  Priest - ordained and empowered to consecrate the sacred Host, absolve from sin (in the confessional), and perform all the Last Rites for a dying or ailing soul.  This is the usual stopping-off point for most who enter into Holy Orders.
8)  Bishop - consecrated and empowered and authorized to make decisions, train, form, and ordain new priests (it is virtually always the bishop who performs Holy Orders, and also who performs the Sacrament of Confirmation.