Where is it in the Consitution? Show me.
It's not directly in the Constitution, but corrupt political authorities, in conjunction with lawyers have twisted the words of the Constitution to meet their own needs. The Religious Freedom clause in the Constitution was set up to protect our government from the Pope. At the time, the Pope was the most powerful man in the world. We didn't want to be under his power. Protestants from Europe established the nation, and therefore wanted to keep the Catholic Church from meddling in governmental affairs. Also, by keeping religion out of the government, the Constitution effectively destroys the "ruling by devine right" excuse.
Here's a quick example of how badly politicians skew the Constitution. (Mind you, the following example has NOTHING to do with what I'm ranting about, it's just a simplified example.)
public void showStupidity(String name1, String name2)
{
name1: Cows produce methane gas. Methane gas contributes to the hole in the Ozone layer of the Earth. Therefore, cows are contributing to the hole in the Ozone layer of the earth.
name2: This just in, name1 is on a relentless vendetta against all cows. He said that cows are contributing to the hole in the Ozone layer of the Earth, therefore changing their national image, and is making people hate cows so they would kill them.
}//End example.
Above was an example of what politicians MIGHT do in that situation to bolster their own public image. The politician will also use his ties with the media and other connections to have Scientist Pete silenced, so the Politician's vendetta against polluting cars can continue.
In the terms of the Constitution, while separating church and state, people tend to view this as "Abandon religion at all costs" and therefore make every effort to have any religious symbols from any religion deleted from anywhere within, or around any governmental establishment. Our major laws revolve around the 10 commandments and the 7 Pilars of Islam, and more. Are we to do away with all laws and become a complete anarchy because we follow some morality within two or three religions?