The Establishment Clause states that "Congress shall make no law respecting an establishment of religion" thus preventing it from establishing a religion but the state of Louisiana isn't Congress. In the strictest reading, the Establishment Clause proscribes any adoption of an official religion by the federal government. Doesn't say anything about a state government.
However, in a number of decisions, the Supreme Court held that because of the Fourteenth Amendment, the protections of religious freedom in the First Amendment are enforceable against state and local governments. While the U.S. Constitution does not mention God, nearly all state constitutions reference either God or the divine. It will be interesting to see what Louisiana does when other religious group claim their right to equality under the Constitution.
Moreover, nearly every Christian is going to hell if you look at the 10 commandments from the perspective that Moses was a Jew.