For Catholics, the first important statements on church views of Darwin came with the papal encyclical Humani Generis ("The Origin of Humanity"), published by Pius XII. In this document, the Pope acknowledged that God might have used evolution as the mechanism of creation, and therefore Darwin's theories did not necessarily contradict faith. But, Pius XII said, evolutionary theory is insidious because it can be used to argue against the existence of God. Pius XII called evolution a serious hypothesis whose drawback was that it "has not been fully proved even in the domain of natural sciences," a description that still pertains today. He went on, however, to complain of "fictitious tenets of evolution which repudiate all that is absolute, firm and immutable" and to protest that "the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all." Humani Generis concluded with the dictum that Catholics could teach and learn Darwin's ideas about how existing living things change, but that the view that humanity is entirely natural in origin must "not be advanced in schools, in conferences or in writings of any kind, and that they be not taught in any manner whatsoever to the clergy or the faithful."
Papal views of Darwin came closer to biology department views with Pope John Paul II's 1996 speech to the Pontifical Academy of Sciences. This teaching, called Truth Cannot Contradict Truth, argued that faith should never fear any scientific finding, even one that upsets cherished views. Scientific truths, the Pope said, must be taken as they are because they add to the world's store of truths.
At the 1996 session the Pope allowed that "new knowledge has led to the recognition of the theory of evolution as more than a hypothesis," noting that the idea of natural selection "has been progressively accepted by researchers, following a series of discoveries in various fields of knowledge." John Paul II all but endorsed natural selection as a description of how animals evolve, but found the theory wanting as an explanation of the soul, rejecting "theories of evolution which, in accordance with the philosophies inspiring them, consider the spirit as emerging from the forces of living matter or as a mere epiphenomenon of this matter." The soul, the Pope said, must arise divinely, in ways that science does not see. With this teaching, John Paul II staked out what might be called the modified limited religious endorsement of evolution: that it exists but only explains the biological part of us, not the spiritual mystery. Interestingly, in this teaching the Pope said nothing about Adam, the Garden, or the Genesis account of creation. Since what is significant about papal pronouncements is often what is not said, the Pope's 1996 reasoning seemed to back the church away from its previous insistence on a sudden, from-nothing creation of humankind.