I don't know about you, but I went to public school for 12 years and god and religion to my knowledge was never taught by the curriculum. But that has not always been the case in America. Until McCollum v. Board of Education (1948), school districts all over America had religious classes taught. Children had to opt out of the class, and were often ostracized for doing so. One Illinois woman, Vashti McCollum, took the issue all the way to the Supreme Court when her son was made to sit in the hallway and principle's office and bullied by his classmates for opting out of the religious classes. The decision by the court that this was unconstitutional lead to the banning of all religious lessons in public schools and was one of the first times the high court extended the establishment clause in the First Amendment to the states.
Justice Hugo Black wrote in the courts opinion:
Neither a state nor the Federal government can, openly or secretly, participate in the affairs of and religious organization or groups and vice versa. In the words of Jefferson, the clause against establishment of religion by law was intended to erect "a wall of separation between church and State."
Although the battle had been won, evolution was still banned from being taught in Arkansas public schools as per the results of the 1925 Scopes case in Tennessee, and that didn't change until 1968. Small battles continued to erupt across the US over religion and creationism in public schools, notably the recent Kitzmiller v. Dover case that declared "intelligent design" just creationism in disguise and not a valid scientific theory to be taught in public schools and therefore, unconstitutional. Still, the faithful never rest, and the fortification of the "wall of separation" will always need constant vigilance.