Your post reminds me of a passage I read recently in a book titled The Church of Our Fathers, by Roland H. Bainton. It's a fascinating book ,by the way, and chronicles the history of the church from Jesus to present-day.

The book tells of when the doctrine of the trinity originated, and how. I will quote it here:

"A quarrel broke out among the Christians themselves about the relations of the Christ, God, and the Holy Spirit. All Christians were agreed that God is one. There could be no quarrel on this point. But what was the relation of Christ to God? Although Christ lived on earth in a real body, and really suffered and really died, yet he also rose from the dead and brought new life to those who trusted in him. Surely, then, he must have been much more than ordinary man. But if he were God, would there not be two gods? And is not God's Spirit working in our hearts also God? In which case are there three gods?

The dispute became heated in the city of Alexandria, where an aged priest names Arius claimed that Christ was indeed more than a man, but less than God. A young deacon in the same church, Athanasius by name - he became bishop and is shown in the previous picture in his bishop's robes - said that the views of Arius would never do. If Christ were more than man and less than God, he would be neither one nor the other. Athanasius said that there is one God. Christ shared in the being of God. So also does the Christian, through Christ who shares completely and helps usto share more fully. The spirit shares completely too. God is one. But within the One are three, sharing in his being: the Father who is the Lord of all the universe, the Son who lived on earth and for us died and rose, and the Spirit who breathes upon our spirits and teaches us the things of God.

The three who thus share in the being of God are called the Trinity.

...The dispute as to the relationship of Christ and God was settled according to the views of Athanasius." (pages 41-42, 45)

 

The author also goes a little into celibacy and monogamy, although the changes in the church were very gradual, as it is spread out over several chapters. But it is interesting to note that the importance of celibacy came before the monogamy decrees. It began with a group known as the "Gnostics."

 

"Another type of religion in the Roman Empire was quite different and refused to see any signs of God in the world of nature. The world, said this religion, is bad. In it are flies and fleas and fevers. No good God would have made it. Our bodies are bad and the thing for us to do is to make them as miserable as we can until we can get rid of them. When people with these views became Christian, they carried over some of their ideas and said that since the body is bad and Jesus is good, he cannot have had a body - not a real one. Jesus, they said, was not really born, did not really suffer and die and rise. These people were called Docetae, from the Greek word meaning "to seem," because they said Jesus just seemed to have a body. They were also called Gnostics, from the Greek word meaning "to know," because they said that the way to rise above the body is to know more. They were proud of all they knew and delighted in philosophies, astrology, and magic." (page 26)

 

Gnosticism paved the way for the monks and hermits. Monks and hermits in turn led to monasteries and nunneries. Keep following the path and you find priests and bishops and eventually the pope, who was originally just another bishop.The influence of Gnosticism makes me sick to my stomach, because it literally pervades everything, even things I was taught as a child about what heaven will be like. It was the pope who made it law for all clergy to be celibate, and he eventually had to resort to underhanded manipulation to get it passed because many bishops were married and refused to obey it.

 

There is much more about the origin of monogamy at this link:

 

Monogamy basically resulted from compromise by the Catholic Church, just as much as every other "tradition" they uphold.