As Mr. Furches has already pointed out "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof".
In the First Amendment you will not find the words "religious liberty" however courts have found the the PRINCIPLE for religious liberty exists behind the First Amendment. The point of such amendment is twofold. First, it ensures that religious beliefs - private or organized - are removed from attemted government control. This is why the government cannot tell either you or your church what to beleive and teach. Second, it ensures that the government does not get involved with enforcing, mandating, or promoting particular religious doctrines. When our forefathers wrote the Constitution they wanted to stay away from the problems that was created in Europe when you have government "Established" churches.
Can anyone deny that the First Amendment guarantees the principle of religious liberty, even though those words do not appear there? Similary, the First Amendment guarantees the priciple of the separation of church and state - by implication, because separation of church and state is what allows religious liberty to exist. In which also many people think the Constitution states "separation of church and state" which does not appear either. Nor does any where in the Constitution does it say we have the "right to privacy" or the "right to a fair trial", the amendments are setting up the conditions for fair trials, and right to privacy these are just a couple of many examples.
Three foundations where used when writting the constitution; Inherent Rights, Self Government, and Seperation of Powers. I will only speak of the Inherent Rights- Rights that ANYONE living in America has - Its says, nothing about color, religion, Alien, Us Citizen, age, level of education it simply says that everyone has the same rights while in America.
So some would say is this his right to have a beard because of his beleifs. Some would say he's not American so he don't have any rights. I don't know the answer, but most rules are established for the betterment of the majority, and not on a indiviual bases to please one. I grew up in the late 70's early 80's and I remember getting a coaches haircut because my hair was a little to long. It was the RULE.