What scriptures to post in courtrooms, on lawns, etc.

"For some reason, the most vocal Christians among us never mention the Beatitudes (Matthew 5). But, often with tears in their eyes, [they] demand that the Ten Commandments be posted in public buildings. And of course, that's Moses, not Jesus. I haven't heard one of them demand that the Sermon on the Mount, the Beatitudes, be posted anywhere.
"Blessed are the merciful" in a courtroom? "Blessed are the peacemakers" in the Pentagon? Give me a break!”
― Kurt Vonnegut, A Man Without a Country (source)

Vonnegut, probably not a believer himself, had a point.

Some people have deeply committed themselves toward placing the Ten Commandments in courtrooms, or in or next to other public buildings. See Roy Moore for a widely publicized example.

Why do people do this? I can only speculate. Some, no doubt, believe that the Ten Commandments are a foundation for our laws. Some want to honor God. Some are probably desiring to see the Commandments posted for their own political advantage. Some want the U. S. to be an explicitly Christian nation. There are probably other reasons. On the other hand, government often sees posting of the Ten Commandments as putting one religion ahead of another, and has banned the practice.

The Ten Commandments, with the exception of the Command to honor one's parents, are warnings against sins of commission -- don't commit adultery, don't give false testimony in court, don't worship idols, don't want other people's possessions, etc. Sins of commission are, generally, easy to spot. Either I have stolen from someone, or I haven't. So, laws against things are often easier to enforce than laws for things. But there are also sins of omission. Things that we should do, but don't. Let's look at some other possibilities for posting publicly, as Vonnegut suggested.

How about the Beatitudes?
Matthew 5:3 “Blessed are the poor in spirit,
for theirs is the Kingdom of Heaven.
4 Blessed are those who mourn,
for they shall be comforted.
5 Blessed are the gentle,
for they shall inherit the earth.
6 Blessed are those who hunger and thirst after righteousness,
for they shall be filled.
7 Blessed are the merciful,
for they shall obtain mercy.
8 Blessed are the pure in heart,
for they shall see God.
9 Blessed are the peacemakers,
for they shall be called children of God.
10 Blessed are those who have been persecuted for righteousness’ sake, for theirs is the Kingdom of Heaven.
(Text notes in the World English Bible indicate that the first three of these are based on the Old Testament: 5:3 on Isaiah 57:15 and 66:2, 5:4 on Isaiah 61:2 and 66:10,13, and 5:4 on Psalm 37:11. So Vonnegut isn't completely correct about the source of the Beatitudes. But, mostly, he is. It was Jesus.)

The Beatitudes are not mostly about not doing things, but about doing things, or about our attitude: being merciful, making peace, hungering after righteousness, etc. We may respect, honor, and try to follow the standard of the Beatitudes, but we don't make laws commanding people to be pure in heart, or to be gentle, and, if we did, they would be most difficult to enforce. But maybe it would be a good idea to post these in courtrooms, except that doing so would tend to violate them -- it might not be making peace, or being gentle.

There are some other candidates for such posting, if it were allowed.
One such is the Golden Rule, which, like the Beatitudes, comes from the Sermon on the Mount:
Matthew 7:12 Therefore whatever you desire for men to do to you, you shall also do to them; for this is the law and the prophets.

Here's another, from the Old Testament:
Micah 6:8 He has shown you, O man, what is good.
What does Yahweh require of you, but to act justly,
to love mercy, and to walk humbly with your God?
That doesn't come from Moses, but would presumably, not be offensive to Jews or Muslims, or Christians. But it's similar to the Beatitudes, in that it's about out attitudes, not about things we shouldn't do.

And then there's St. Paul, in Galatians 5:22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faith, 23 gentleness, and self-control. Against such things there is no law. The Fruit of the Spirit is, again, about our attitudes. And, instead of outlawing various behaviors, it, as it were, inlaws them. The Fruit of the Spirit is not from the Law of Moses, but it is compatible with it. Read on:

In Matthew 22, Jesus stated the two most important commandments:
37 Jesus said to him, “ ‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’ (Deuteronomy 6:5) 38 This is the first and great commandment. 39  A second likewise is this, ‘You shall love your neighbor as yourself.’ (Leviticus 19:18) 40 The whole law and the prophets depend on these two commandments.”
These two are also not so much about what we shouldn't do, but about what we should. And they are from the Mosaic Law, as quoted by Jesus. People who want to put signs in their front yard, or on their wall, or even in a courtroom, should consider these alternatives!

Thanks for reading!