So you still cannot figure it out.
Polygamy and concubage were practiced in Christianity in different all through the biblical period and history proves it continued for up to a 1000 years after.
Monogamy was the norm among Christians. However, in the context of the sickness of a wife preventing matrimonial intercourse,
Martin Luther, the founder of the Protestant Reformation, wrote: "I confess that I cannot forbid a person to marry several wives, for it does not contradict the Scripture. If a man wishes to marry more than one wife he should be asked whether he is satisfied in his conscience that he may do so in accordance with the word of God. In such a case the civil authority has nothing to do in the matter.
The Church held a
synod in Hertford, England, in 673 that was supervised by
Archbishop Theodore. Chapter 10 issued by the synod declared that marriage is allowed between one man and one woman, and separation (but not divorce) is only granted in the case of adultery, but even then remarriage is not allowed.
The Roman councils of 1052 and 1063 suspended from communion those laymen who had a wife and a concubine at the same time.
In Scandinavia, the word for an official concubine was "frille". Norwegian Bishop
Øystein Erlendsson (ca. 1120–1188) declared that concubines were not allowed to accept the sacraments unless they married, and men were forced to promise marriage to women they had lain with outside of wedlock. In 1280, the Norwegian king
Eirik Magnusson (1280–99) declared that men were exempted from having to promise marriage to the frille if they went to confession and did penance. The Church answered by making several declarations in the 14th century, urging men to marry their concubines. In 1305, King
Håkon V (1270–1319) issued a law that declared marriage to be the only lawful way of cohabitation, and declared that only women in wedlock were allowed to dress as they pleased, while the dress of concubines was restricted.
Lutheran theologians approved of
Philip of Hesse's polygamous marriages to
Christine of Saxony and
Margarethe von der Saale for this purpose, as well as initial disapproval of divorce and adultery. (1545)
Anabaptist leader
Bernhard Rothmann (1535) initially opposed the idea of plural marriage. However, he later wrote a theological defense of plural marriage, and took nine wives himself, saying "God has restored the true practice of holy matrimony amongst us.
When did Christianity outlaw polygamy and concubiage
A different position was taken by the
Council of Trent in 1563, which was opposed to polygamy and concubinage: "If anyone says that it is lawful for Christians to have several wives at the same time, and that it is not forbidden by any divine law (Matt. 19:4f): let him be
anathema".The polemicist
John Milton expressed support for polygamy in his
De doctrina christiana.