Born on March 1, 1920, in Cotija, Michoacán, Mexico, Maciel was ordained as a Catholic priest in 1944. He went on to found the Legion of Christ, a conservative Catholic congregation, in 1941. The organization gained significant influence within the Catholic Church, with Maciel at its helm. He became a prominent figure, rubbing shoulders with high-ranking clergy, including Pope John Paul II and Cardinal Joseph Ratzinger (now Pope Emeritus Benedict XVI).