Fray Servando Teresa de Mier (1763-1827) was a 31-year old ordained priest of the Catholic Dominican Order with a Doctorate of Theology, when he was invited by the Mexico City Council to offer a sermon December 12, 1794 at the Collegiate Church of Guadalupe, to honor the Virgin of Guadalupe tradition. Fray Servando Teresa de Mier: Writings on Ancient Christianity and Spain's Evangelism of Mexico translates Fray Mier's Spanish writings published in 1876 by Mexico's State of Nuevo Leon and the Autonomous University of Nuevo Leon. The primary text is Fray Mier's "Apologia," his defense of his Guadalupe Sermon with speeches to Mexico's First Constituent Congress. Dr. Mier states in his "Apologia" that his Sermon set forth two propositions: 1st that the Gospel of Jesus Christ had been preached in America centuries before Spain's conquest by Saint Thomas, whom the Indians called Santo Tomé, or Quetzacoatl in the Mexican language; and 2nd that the image of Tonantzin, Mother of the True God, given to be known to the Indians by Santo Tomé, was identical to that of the Virgin of Guadalupe. The Sermon caused Fray Mier to be accused of denying the Virgin of Guadalupe tradition, which triggered removal of his Doctor degree, Ecclesiastical suspension of his license to preach, imprisonment, exile, and Inquisitions for 27 years. Fray Mier's writings are authentic Mexican history. Sadly, it is hidden history that when cited, without research, has been called Christian myth. This is the first publication in English of Fray Mier's "Apologia," in which he writes: "If these things appear deliriums, they do not appear so much to those who have studied our antiquities." Let's begin to study Mexican Christian antiquities!