But there's no guarantee.
:think:
that any relationship works out
There's a far better chance of the relationship working out when A) there's a foundational commitment, marriage, in place, and B) when there's a deterrent in place against breaking that foundational commitment.
and there's plenty of marriages that break down beyond repair even without infidelity being part.
Sure. And that's caused by the government simply having "no-fault" divorces as a way out.
It's currently too easy for a married couple to say "I give up on trying to maintain this relationship," instead of "Our relationship is failing, is there anything I can do to strengthen it."
There's plenty of non married couples with children who have very stable relationships who aren't harming themselves or their children
This is both begging the question and special pleading. Begging the question, because you're assuming that they aren't harming themselves or their children (something you need to prove), and special pleading, because you're ignoring all the non-married couples with and without children who do not have stable relationships and/or ARE harming themselves and their children.
Studies have shown that children who grow up without both parents in the home and/or in a married relationship are worse off then children who grow up with both parents in the home and married.
https://ifstudies.org/blog/when-it-comes-to-child-well-being-is-one-parent-the-same-as-two
and they're not unmarried to "shake their fists at God" or some such.
That's what they're doing, whether that's their intent or not.
That's just you projecting your own beliefs onto other people.
God said:
Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh. - Genesis 2:24
http://www.biblegateway.com/passage/?search=Genesis2:24&version=NKJV
By doing otherwise, couples disobey God, whether they acknowledge Him or not.
There's plenty of married people who have committed relationships
As I said above, sure, people can be in committed relationships.
But there's no foundation for it.
It's like trying to build a house upon sand, rather than rock.
And I'm sure you remember what Jesus said about that:
[JESUS]“Therefore whoever hears these sayings of Mine, and does them, I will liken him to a wise man who built his house on the rock:and the rain descended, the floods came, and the winds blew and beat on that house; and it did not fall, for it was founded on the rock.“But everyone who hears these sayings of Mine, and does not do them, will be like a foolish man who built his house on the sand:and the rain descended, the floods came, and the winds blew and beat on that house; and it fell. And great was its fall.”[/JESUS] - Matthew 7:24-27
http://www.biblegateway.com/passage/?search=Matthew7:24-27&version=NKJV
as well so this is no way a criticism of marriage itself
By making the argument that men and women don't need to get married to raise a family, you inherently make marriage out as being unnecessary.
but rather that of implementing a law that has no place in modern society.
Saying it doesn't make it so.
Saying it doesn't make it so.
If you were to introduce a law like that in the present day then there's only one result, a reduction in the rate of people getting married.
The evidence says otherwise.
Two modern countries (even with corruption in their enforcement of laws) have the death penalty for adultery, and their marriage rates have not fallen to zero.
OUR country, on the other hand, has all but abolished the death penalty for adultery, and our divorce rates have skyrocketed, our marriage rates have gone down, and it's caused more murders by enraged spouses.
Most people don't want society governed by "religious" laws
Argumentum ad populum.
and all you'd have succeeded in is encouraging people not to bother getting married. Ironic.
Saying it doesn't make it so, Arthur. And in fact, the evidence shows the opposite of your claim, that marriages are longer lasting, and that there is hardly any adultery, and that there is hardly any divorce, and that the marriage rate has not dropped to nearly zero.