This is false. What was declared was that it could not be prayer from the platform of the school. If someone wants to privately pray in school, there is nothing preventing such.
I posted
this link earlier, but I am not sure if you saw it, it outlines why the pervasive myth of a Christian nation is false. One of the most important things to look at is that we were a country that invoked no divine favor in our current Constitution. Many saw that as a terrible shortcoming of the system of government that we now live under. "In the light of these documents, it's easy to see just how unique, unusual, even unprecedented the Constitution is. The United States of America was the first modern republic that was created on the foundation of reason, without seeking blessings from a god, without imploring divine assistance or invoking divine favor. And, as I said, this fact was not overlooked when the Constitution was being debated. Very much to the contrary, the religious right of the founding generation angrily attacked it, warning that ratifying this godless document as-is would spell doom for the nation."