Modern canon law of the Latin Church (a faction that keeps faith with the papacy) states:
Clerics are obliged to observe perfect and perpetual continence for the sake of the kingdom of heaven and therefore are bound to celibacy which is a special gift of God by which sacred ministers can adhere more easily to Christ with an undivided heart and are able to dedicate themselves more freely to the service of God and humanity.
All the ordained ministers of the Latin Church, with the exception of permanent deacons, are normally chosen from among men of faith who live a celibate life and who intend to remain celibate "for the sake of the kingdom of heaven." Called to consecrate themselves with undivided heart to the Lord and to "the affairs of the Lord", they give themselves entirely to God and to men. Celibacy is a sign of this new life to the service of which the Church's minister is consecrated; accepted with a joyous heart celibacy radiantly proclaims the Reign of God.
In the Eastern Churches a different discipline has been in force for many centuries: while bishops are chosen solely from among celibates, married men can be ordained as deacons and priests. ... Moreover, priestly celibacy is held in great honor in the Eastern Churches and many priests have freely chosen it for the sake of the Kingdom of God.
Do not deprive one another except perhaps by agreement for a set time, to devote yourselves to prayer, and then come together again, so that Satan may not tempt you because of your lack of self-control. This I say by way of concession, not of command. I wish that all were as I myself am. But each has a particular gift from God, one having one kind and another a different kind. To the unmarried and the widows I say that it is well for them to remain unmarried as I am. But if they are not practicing self-control, they should marry. For it is better to marry than to be aflame with passion.