Summoned by Pope Pius IX, Vatican I (A.D. 1869-70) condemned, as erroneous, philosophical naturalism, pantheism, materialism, and atheism. It also affirmed each successor to the chair of the St. Peter obtains the primacy of Peter: as Vicar of Christ and sovereign head of the Church militant. Image above links to Tanner translation of the decrees. ISBN recommendation: 0-87840-490-2