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.
I think based on necessity and the nature of the minsitry, those who were priests at that time were MOSTLY unmarried. However, to marry or not marry was NOT a rule that was established during the first 3 centuries after Christ. It came many centuries later.
For instance, St. Patrick himself ( Born 385 AD ) was the grandson of a priest and the son of a deacon. St. Hillary was elected bishop of Poitiers (Born 310 ) in what is now France by the laity and clergy. He was already married with one daughter named Apra. And we all know that St. Peter himself was a married man.
We can agree that the rule priestly celibacy came much later but it did not cause much resistance because most of those who took the vocation of priesthood were like St. Paul, unmarried.
Well, that your opinion. Peter was married (Matt. 8:14). Philip the evangelist was married (Acts 21:8,9). Paul instructed Timothy that a bishop was to be the husband of one wife (1Tim. 3:2).
That was quite a while before 400 AD.
Now, up in my old neighborhood in IL, there was a priest that left the boys alone ( I hope), but borrowed more than one man’s wife during his assignment to the local RCC. He was moved elsewhere when it became too obvious.