Brennan, a Roman Catholic, did not publicize his own religious affiliation, but declared, "I'm too old not to be a religious fella. [...] It appears we are losing something a lot of people made a lot of sacrifices for." In 1964, Brennan spoke at "Project Prayer", a rally attended by 2,500 at the Shrine Auditorium in Los Angeles. The gathering, hosted by Anthony Eisley, sought to flood Congress with letters in support of mandatory school prayer, following two decisions of the Supreme Court in 1962 and 1963 that had struck down the practice of mandatory prayer in public schools as being in conflict with the Establishment Clause of the First Amendment to the United States Constitution.