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Unhappy with the direction of the commission, the Vatican packed the last commission meetings with fifteen bishops to formulate the final recommendation to the pope. But even the bishops voted nine to three (three abstained from voting) to change the teaching, concluding that the popes’ previous teaching on birth control were not infallible and that the traditional theological basis for the prohibition of contraception was invalid. They declared that responsible parenthood was an essential part of modern marriage and that the morality of sexual acts between married couples was not dependent “upon the direct fecundity of each and every particular act” but must be viewed within the totality of the marriage relationship.

Despite the commission’s years of work and theologically unassailable conclusion that the church’s teaching on birth control was neither infallible nor irreversible, Pope Paul VI stunned the world on July 29, 1968, when he reaffirmed the church’s ban on modern contraceptives in Humanae Vitae (Of Human Life). He declared that “each and every marital act must of necessity retain its intrinsic relationship to the procreation of human life.”

The pope had deferred to a dissenting minority report prepared by four conservative theologian priests on the commission that maintained contraception was a “sin against nature” and a “shameful and intrinsically vicious act.” These theologians said that church could not change its teaching on birth control because admitting the church had been wrong about the issue for centuries would raise questions about the moral authority of the pope, especially on matters of sexuality, and the belief that the Holy Spirit guided his pronouncements. “The Church cannot change her answer because this answer is true. … It is true because the Catholic Church, instituted by Christ … could not have so wrongly erred during all those centuries of its history,” they wrote.

As one of the conservative theologians famously asked one of the female members of the commission, what would happen to “the millions we have sent to hell” for using contraception if the teaching were suddenly changed?

The Church cannot change her answer because this answer is true. Whatever may pertain to a more perfect formulation of the teaching or its possible genuine development, the teaching itself cannot be substantially true. It is true because the Catholic Church, instituted by Christ to show men a secure way to eternal life, could not have so wrongly erred during all those centuries of its history. The Church cannot substantially err in teaching doctrine which is most serious in its import for faith and morals, throughout all centuries or even one century, if it has been constantly and forcefully proposed as necessarily to be followed in order to obtain eternal salvation. The Church could not have erred through so many centuries, even though one century, by imposing under serious obligation very grave burdens in the name of Jesus Christ, if Jesus Christ did not actually impose those burdens. The Catholic Church could not have furnished in the name of Jesus Christ to so many of the faithful everywhere in the world, throughout so many centuries, the occasion for formal sin and spiritual ruin, because of a false doctrine promulgated in the name of Jesus Christ.

If the Church could err in such a way, the authority of the ordinary magisterium in moral matters would be thrown into question. The faithful could not put their trust in the magisterium’s presentation of moral teaching, especially in sexual matters.