When looking at the First Amendment we see 5 parts: establishment of religion, free speech, free press, right to assemble, and right to petition for a redress of grievances. If you are unfamiliar with the First Amendment you van view it here.
Everyday we hear the left talking about the right to free speech, free press, to assemble, to petition, and the separation of Church and State. I understand four out of the five. In the First Amendment we see that the Church is to be protected from interference from the state, not the other way around. The First Amendment states that, "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof." The government can't make any laws stating that, for example, the US is a Catholic country, or create a Church of America. Also, the government can't make any laws which keep people from praticing their religion, like when the English banned the parties of the Catholic faith.
So where does this separation of Church and State come from? The phrase was introduced to the American political landscape by Thomas Jefferson in a letter to the Danbury Baptists. Jefferson writes, "I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should 'make no law respecting an establishment of religion, or prohibiting the free exercise thereof,' thus building a wall of separation between Church & State."
Jefferson reassured them that they could be free to parties their religion without governmental interference. Today the secular forces in America are using this idea of separation to achieve goals which are the exact opposite of what the term meant in 1802.
The secularists push to have religious symbols removed from public lands, and ban prayer in schools. The cases Engel v. Vital in 1962 and Abington Township v. Schempp in 1963 effectively banned prayer in schools, and are now being used to remove crosses from public lands (lets ignore the fact that they have no problem with symbols from other religions on public land). They claim that the Establishment Clause forbids making an official church and therefore bans schools from doing a prayer from any religion. What they ignore is the Free exercise Clause. If a group of people wish to pratice their religion don't they have a right to do so? Doesn't banning religion from public places violate Free exercise, Free Speech, and Right to assemble?
What the secularists are doing is trying to minimalist the importance of religion in private and public life. Through boycotts and lawsuits from groups like the ACLU, they have bullied their secular belief onto everyday Americans. They claim that they are protecting the rights of different religious, but they do it by ignoring the rights of Christian Americans.