Source: The Guardian
After the Apollo 8 crew had read out the Genesis creation account in orbit, Madalyn Murry O'Hair wanted a ban on NASA astronauts practising religion on earth, in space or "around and about the moon" while on duty. She believed it violated the constitutional separation between church and state.
In Magnificent Desolation, Buzz Aldrin explains how astronaut Deke Slayton, who ran the Apollo 11 flight crew operations, told him to tone down his lunar communiqué. "Go ahead and have communion, but keep your comments more general," he advised. Looking back Aldrin writes that the communion was his way of thanking God for the success of the mission. Yet, later he hinted that he could have been more inclusive:
"Perhaps, if I had it to do over again, I would not choose to celebrate communion. Although it was a deeply meaningful experience for me, it was a Christian sacrament, and we had come to the moon in the name of all mankind – be they Christians, Jews, Muslims, animists, agnostics, or atheists."
O'Hair's case against Nasa eventually fizzled out, but it dramatically changed the tone of the Apollo 11 landing. Aldrin had originally intended a much more pioneering Christopher Columbus-style ceremony on the moon. That was never to be.