Jesuit Historian, George T. Dennis SJ of Catholic University of America says: “There is simply no clear evidence of a general tradition or practice, much less of an obligation, of priestly celibacy-continence before the beginning of the fourth century.” (SEE HIS WORK: The Apostolic Origins of Priestly Celibacy, Theological Studies, 52:4 (1991:Dec.) p.738 )
Another Jesuit Priest Peter Fink SJ agrees, saying that underlying premises used in the book, Apostolic Origins of Priestly Celibacy, “would not stand up so comfortably to historical scrutiny”. Dennis says this book provides no evidence that celibacy had apostolic origins.
Of course one can always argue that they, like Francis are all liberal Jesuits...
But then, another catholic theologian, Monsignor Philippe Delhaye wrote:
“During the first three or four centuries, no law was promulgated prohibiting clerical marriage. Celibacy was a matter of choice for bishops, priests, and deacons. ... The apostolic constitutions (c. 400) excommunicated a priest or bishop who left his wife ‘under pretense of piety’ (Sacrorum Conciliorum nova et amplissima collectio 1:51) — SEE “Celibacy, Clerical, History of” in New Catholic Encyclopedia, vol 3, Catholic University of America: Washington, D.C. 1967 p.370
Even if Fr. Dennis’ premise is accepted, the beginning of the 4th century is hardly 1000 years after Christ. The truth is that what is missing from those early years is prove of formal legislation. But it would be absurd to think that such latter legislation could have imposed such a drastic change without causing a major controversy and resistance, of which there is no evidence. The latter legislation could only have been peacefully received if it had reflected what was already the accepted practice.