So, where did Christians get the idea marriage is between 1 man and 1 woman?

Some one said it, they believed it regardless of how absurd it is, since that is what they want to believe.

God. Genesis 2 and then Jesus said it was that way from the beginning. Just because Solomon had more does not make it right. When God chose parents for His Son, He chose one man and his wife. When God set leaders in the local church, they were to be husbands of one wife. This stuff isn't hard unless you don't want to follow it.

Matthew 19:1-12 speak on the topic of marriage and polygamy was not condoned but allowed in order to care for those that were widowed and had no one to take care of them. So many were taking on wives and divorcing them for no reason. So Jesus came and set the record straight, to let them know marriage is suppose to be between One man and One woman and the only grounds for divorce was adultery or death.

Adam and Eve as taught by Jesus. There is subtle but clear condemnation of Solomon. Perhaps you think that everything mentioned in the Bible is done so as approval. That is not so.

I believe that the earliest Christian writings were always monogamous as they were basically Hellenist -- ie: it was based on Greek and Roman cultural morays.

Check some New Testament material.

Of-course, the New Testament frowns on marriage altogether.

Paul's famous line is "its better to marry than to burn" --

ie: he sees marriage as a surrender to uncontrollable sexual urges.

If marriage is seen solely as a way to deal with an uncontrollable itch, and to deal with it in as limited a fashion as possible - then polygamy is not justifiable.

The Jewish ancient religious law allows polygamy but frowns upon it from a relationship building point of view

(in every story in the Hebrew Bible that includes polygamy as part of the story, the polygamy is a component that drives the story to tragedy,

the Hebrew word for "sister wife" has the same linguistic root as the Hebrew word for trouble)

Starting about a thousand years ago, the Jewish courts held that from a practical point of view no one was capable of having a polygamous relationship that fit the legal requirements for a valid Jewish marriage -- and therefore made them illegal by legislative enactment.

I'm surprised that you're asking,

because every 'christian' on here is going to be copy-&-pasting a biblical quote, and it's location.

The fact remains that the bible is wrong, and none of what the parables say ever happened.

Based on this,

it is safe to conclude that no matter how many "Our Father" & "Hail Mary" prayers anyone says,

*God* is not listening for them, and won't exactly be paying any "high dividends" to christians for

something that He doesn't care about.

Therein, the bible "as an entity"

is useless and meaningless, and the 'christianity' that is based on it ... should simply, end.

We get it from the definition that God gave to marriage when he first created the concept in Genesis chapter 2. He stated there that it was to be between a man and a woman. Jesus repeated that twice in his teachings also.

That other people who are not God decided to try and make marriage something else (such as polygamy or a series of marriages and divorces) Just like the SCOTUS deciding that marriage is to between two people of the same sex does not make that a marriage.

Yes, we get it from the Bible. Just because people sinned and tried to redefine marriage (and failed) does not mean that the definition that God gave it is not there.

Try actually reading the book sometime instead of just parroting the talking point that you have been brainwashed with. You will not look so foolish.

from the bible, one Adam and one Eve.

For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh.

A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach;

Let the deacons be the husbands of one wife, ruling their children and their own houses well.

Let not a widow be taken into the number under threescore years old, having been the wife of one man,

if any be blameless, the husband of one wife, having faithful children not accused of riot or unruly.

Atheists don't usually try to justify their immorality with the bible.

Christains receive from Christ.

Surely not hard for you to comprehend?

And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female,

And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?

Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder.

The bible would have us think Brig Young was right. biblical 'marriage' is between a man and his many women.