Let us suppose you are the member of a church for over ten years. During that time, you have the same pastor, who accepted you in membership, married you, and baptized all your children.
Now all of a sudden it turns out that the church officials who ordained your pastor had been guilty of gross immorality at the time, and because of that, those officials are expelled from your denomination and go to jail. Your pastor is devastated and so is your congregation.
Since it turns out that your pastor was ordained by people who were grossly immoral, was the ordination valid? In other words, does your pastor have to be ordained again to remove the taint?
The historic church answered this question no.
The ordination is valid, because the ordaining authorities acted with delegated authority from the church.
This Is a Modern Scenario About an Ancient Heresy
The heresy is called Donatism
During the persecution of Diocletian, many Christian clergy were unwilling to become martyrs and compromised themselves, worshiping idols and handing over sacred books. One of them repented, returned to the church, was reinstated, and was made a bishop—but many Christians were outraged and selected their own bishop, who quickly died and was replaced by Donatus.
According to the Donatists, the morals of the officiating clergy determine the validity of the rite, which is why they did not accept the authority of the repentant bishop, or the authority of any priests he had ordained after he had been restored. In a modern context, if a duly authorized member of the clergy officiated at a wedding or an ordination, even if they did it properly, modern Donatists would consider the wedding (or ordination) to be invalid if it turns out that the celebrant had not lived up to the church’s standards.
Why It Was Considered a Heresy
This seems to guard the morals of the clergy, but it is a fundamental misunderstanding about delegated authority. The clergy are not magicians, they are just deputized agents of the Church (or of God) and thus their authorized actions are valid, even if they aren’t.
If it turns out that the police officer who issued you a speeding ticket was in a drug ring, the officer is expelled from the force and sent to jail, but you still have to pay the ticket. If you are married by a minister who later turns out to have frequented houses of the horizontal profession, the minister is relieved of their credentials, but your marriage certificate is still valid. The policemen and the minister did not possess any personal power, except what was delegated to them, so the power that issued the ticket was the police department, not the individual officer, and the power than married you was the church, not the particular minister.
Calling it a heresy seems a bit over the top, but imagine the ripple effect. Twenty years after he dies, a high church official is found to have been corrupt. Under Donatist thinking, his ordinations would be retroactively invalid, even though they were properly done. If he had ordained your pastor, your pastor would retroactively be a lay person, you would retroactively no longer be a church member, your marriage would be retroactively invalid, and your children would be retroactively illegitimate.
Even worse than the ripple effect, Donatism implies that a person’s sin can nullify the acts of the church and the grace of God. Surely God is more powerful than sin!
Bottom line: clergy are not people with magical powers, they are just people with delegated responsibility. They are functionaries, not wizards.