The Establishment Clause prohibits Congress from defining an official religion. This makes it so the United States government cannot favor one religion over another. This clause was made to further enforce the constitutional right to freedom of religion as guaranteed by the 1st Amendment.
This case further defined the interpretation of the Establishment Clause. While this case didn't make an official ban of all prayer in public schools, it was and continues to be a building block and precedent for similar cases to come.
In my humble opinion, I agree with the ruling of the Fifth Circuit and Supreme Court. While I am a christian myself, I firmly believe that anyone should be allowed to practice their own religian and not have another forced upon them. Especially not in school where kids are only just finding themselves and can be influenced very easily to believe certain things.