There is a very old error that derogates marriage and attempts to forbid marriage. In its extreme form, it forbids marriage of all Christians. In a less extreme form, it forbids marriage of office holders. It is that form that we see in the Roman Catholic church today.
1 Timothy 4:1-3
Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils; speaking lies in hypocrisy; having their conscience seared with a hot iron; forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.
Nuns, Monks, Priests, and Bishops are forbidden in Roman Catholicism (for the most part, though there are a few married priests in some of the other rites besides the Latin rite) from being married. This is an error and a point at which, while it has a lengthy tradition, the Roman Catholic Church stands against Scripture.
I know the usual objections, and they each have been answered.
Objection: No one is forced to be a priest.
Answer: Agreed. And yet, if one wants to be a priest, one is forced to sacrifice marriage. Furthermore, if God is calling a person to the ministry, one is not free to disregard that call.
Objection: It's not a requirement.
Answer: Yes, it is a requirement. It's a condition precedent to obtaining office.
Objection: No one has a right to be a priest.
Answer: If God has called a man to the ministry, then the man does not simply have a right but the duty to answer God's call.
Objection: It's not against Scripture for the church to ordain only those men who are celibate.
Answer: Yes, it is against Scripture. It's clear from the Scriptural requirements given for the offices of deacon and elder/presbyter/bishop that such men are anticipated ordinarily to be married men who have children (1Ti 3:2 A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach; | Tit 1:6 If any be blameless, the husband of one wife, having faithful children not accused of riot or unruly. ). To eliminate all married men from consideration is to render Scripture void through one's tradition.
Objection: So, you're saying that celibacy is evil.
Answer: No. Not at all. In fact, celibacy (if a gift given by God) can be a great help to ministers and especially to missionaries.
Objection: So, you're saying that renouncing marriage is wrong.
Answer: Not exactly. It is, of course, wrong to make an unconditional oath of celibacy, because God does not promise the gift of celibacy to every man who asks it. Furthermore, Scripture plainly teaches that it is better to marry than to burn. (1 Corinthians 7:9 But if they cannot contain, let them marry: for it is better to marry than to burn.) Therefore, an unconditional renunciation of marriage is a sinful oath, and one that ought to be violated (through marriage, not fornication) to honor God, if one later discerns the absence of the gift of celibacy.
Objection: Celibacy of bishops/priests/monks/nuns is just a discipline, not a dogma.
Answer: There is errant doctrine that informs the errant discipline of celibacy. If the Roman Catholic Church followed the doctrine of Scripture, especially as taught in 1 Timothy 4:1-3, then it would not have this particular discipline.
Objection: The Early Church Fathers did it!
Answer: Agreed. The practice seems to have crept in rather early. It was wrong of them to do it, and it is wrong for folks now to follow them in doing it. Our moral authority is not ancient practice but Holy Scripture. Yet, if it were ancient practice, we'd be guided not by the Early Church Fathers, but by the Apostles who (for the most part) married:
1 Corinthians 9:5 Have we not power to lead about a sister, a wife, as well as other apostles, and as the brethren of the Lord, and Cephas?
That was the apostolic practice and Paul affirms that it is an elder's right to marry. It is his "power."
The practice of requiring those who wish to have office in the church to be celibate is wrong. It is contrary 1 Timothy 4:1-3, it is contrary 1 Timothy 3:2, it is contrary to Titus 1:6, it is contrary to 1 Corinthians 7:9, and it is contrary to 1 Corinthians 9:5. It was wrong when Rome used to require deacons to be celibate (an error that has been corrected, without - of course - admission that is was an error) and it will be good when Rome ceases to make that same requirement of priests (though we cannot say how soon that will happen, there are significant pressures pushing Rome in that direction). Rome is wrong to require such celibacy, Rome is wrong to forbid men and women from marrying, and Rome is wrong to teach that unconditional vows of celibacy are good. On this matter, Rome stands against Scripture. Perhaps this area is an area where Rome can heed the correction of Scripture without admitting its mistake (as it has with respect to deacons). Nevertheless, it should serve to demonstrate to the reader that Rome is not an infallible interpreter of Scripture.