The authority of Christian thought is based in scripture, tradition, reason, and experience, with the Bible and church history as the major sources. The abortion debate in the USA has been closely tied to claims that rely on Christian authority. However, Christians have never held uniform views about abortion. The almost complete silence on abortion in the Bible and by the two most important Christian theologians—St. Augustine in the 5th century and St. Thomas Aquinas in the 13th century—undermine sweeping claims about a definitive Christian position. Dogmatism and ethical certainty on abortion were rare in the past and only became dominant themes in the 19th century. This article examines both intellectual debates in the Church and social conditions that influenced thinking on sexuality, the role of women, and the internal politics of the Catholic Church. In the 19th century, the mostly Protestant medical profession played a pivotal role, not only by creating anti‐abortion politics on a national scale, but by taking the place of the patriarchal family in supervising the behavior of women. Protestant churches in the 20th century became politicized and divided into liberal and conservative factions, in part over questions of contraception and abortion. Evangelical Protestants were not deeply troubled by the prospect of liberal abortion laws until they became politicized for extraneous reasons. Christian attitudes on abortion continue to form a maze, never a straight line, just as in the past.