Celibacy did not begin with the Roman Catholics as it is known that long before the birth of Christianity Ancient Druid and Aztec priest were expected to be sexually abstinent.
Catholic Priests strive to emulate the role and chaste way of life of Jesus Christ who all through his life never married and was referred to as an eunuch (Matthew 19:12 “Some are born eunuchs, some have been made eunuchs by others, and some choose not to marry for the sake of the kingdom of heaven, Let anyone accept this who can.)
First evidence that the Catholic priests didn’t start off being celibate is found in the bible as the disciple of our lord Jesus and now considered by Catholics and indeed all of Christianity as the first pope of the Roman Catholic Church, (Matthew 16:18 “Now i say to you that you are peter, and upon this rock i will build my church and all powers of hell will not conquer it.), Peter, was married.
The bible considers celibacy as a gift,(1Corinthians 7:7 “But i wish everyone was as single, just as i am, but God gives to some the gift of marriage and to others the gift of singleness) and in 1Corinthians 7:32-33 (“i want to be free from the concerns of this life, an unmarried man can spend his time doing the lord’s work and thinking how to please him. 33but a married man has to think about his earthly responsibilities and how to please his wife.”) the bible clearly illustrates why its advisable that priests remain celibate. therefore the first reason why ppriests are celibate is for them to devote more time to serving God and preaching about his works.
The celibacy in the Catholic Church historically started off with a written mandate requiring priests to be chaste AD304, followed by, the Canon33 of the council of El vira stated that “All bishops, presbyters and deacons and all other members of the clerics were to abstain completely from their wives and not have children.
Subsequently, the third action taken into this process the council of Nicaea, convened by Constantine rejected a ban on priests marrying requested by Spanish clerics in AD325. As for the East, the Greek ecclesiastical historians Socrates and Sozomen, who wrote a century after the event, reported that the First council of Nicaea(325) considered ordering all married clergy to refrain from conjugal relations, but the Council was dissuaded by Paphnutius of Thebes. Pope Benedict VIII of the 11th century responded to the decline in priestly morality due to the ban that had been initially lifted by issuing a rule prohibiting the children of priests from inheriting property. Some decades after, Pope Gregory VII issued a decree against clerical marriages.
After some years, the Catholic church finally took a concrete stand on celibacy at the second Lateran council held in 1139 when the rule was approved forbidding priests from marrying and at The Council of Trent which considered the matter and at its twenty-fourth session decreed that marriage after ordination was invalid.