First, let me get a legal disclaimer out of the way: I am not a lawyer. I am a layperson who has an opinion and who can read English. Do not use this post as any kind of legal advice. Seek out a lawyer for that.
Let me first begin by giving the full text of the First Amendment to the US Constitution:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
It is specifically the “Religion” clause that I’m going to tackle. Note what this says about the “establishment of religion.” This requires a bit of historical context.
The original colonies that made up what would eventually become the United States of America were originally people who had been persecuted in England due to their religious beliefs: Quakers would settle in Pennsylvania, Catholics settled in Maryland, Puritans would settle in Massachusetts, and so on.
The United States was not and is not one faith under God. It was many faiths: Catholic and Protestant alike.
England, at the time all of this was happening, specifically had an “official” religion for much of its more recent history. This was usually the Church of England (at least since the reign of Henry VIII), but at various times has also been Catholic (pre-Henry, but also during the time of Mary I, Elizabeth I’s half-sister and at various other times), and whatever the hell Oliver Cromwell was. But there was hardly a time in England’s history that it didn’t have an “official” religion.
For the US, this Amendment made it specifically clear that our Founding Fathers weren’t brooking any of that nonsense. They specifically forbade Congress from establishing any religion as an “official” religion of the US, mostly because they knew that no one would agree what that religion should be. The solution: it should be none of them.
Okay, to put it another way. Let’s say you had walked into a courthouse and had seen this on the wall (assuming you are Christian, that is):
In the name of Allah, Most gracious, Most merciful
Praise be to Allah, the Cherisher and Sustainer of the Worlds
Most Gracious, Most Merciful.
Master of the Day of Judgement
Thee do we worship, and Thine aide we seek
Show us the straight way
The way of those on whom Thou has bestowed thy Grace, those whose portion
Is not wrath, and who do not go astray.
What would your reaction be? For a Muslim, this would be a mindful prayer, and would have a specific meaning to him. To you (a Christian), this might be an effrontery.
So, before you get up in arms about how you’re being persecuted for being a Christian because the Supreme Court ruled that you cannot post the Ten Commandments in front of your town hall, understand that this is to protect your own rights as a Christian/Muslim/Jew/Pagan/Heathen/Atheist.