In today’s world, belief in evolution is everywhere in society. In the past, I have written articles against evolution on this site.
Christians have always believed that humanity started with two actual human beings, Adam and Eve, as recorded in the first book of the Bible, Genesis. The theory of evolution, however, introduced the idea of polygenesis, according to which humanity had more than two ancestors.
Polygenesis undermines the entire faith because it undermines the dogma of original sin.
St. Paul writes in Romans 5:12: “Therefore as sin came into the world through one man and death through sin, and so death spread to all men because all men sinned”. Because Adam sinned against God at the very beginning of humanity, he fell from sanctifying grace. That is, he lost his supernatural relationship with God. All human beings descended from Adam, and have inherited this lack of grace, called original sin. Everyone except Christ and the Virgin, of course.
The Council of Trent declared the following about original sin:
“If any one does not confess that the first man, Adam, when he had transgressed the commandment of God in Paradise, immediately lost the holiness and justice wherein he had been constituted; and that he incurred, through the offence of that prevarication, the wrath and indignation of God, and consequently death, with which God had previously threatened him, and, together with death, captivity under his power who thenceforth had the empire of death, that is to say, the devil, and that the entire Adam, through that offence of prevarication, was changed, in body and soul, for the worse; let him be anathema.” (5th session)
The doctrine of original sin concerns the heart of Christian teaching: why Redemption was necessary for people to go to Heaven. Thus, it is not optional for Christians to believe that humanity began with two real people, Adam and Eve. Pope Pius XII wrote an entire encyclical called “Humani Generis” on this subject. He wrote:
“When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For 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, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.” (Humani generis 37)
Although Pius XII wrote in his encyclical that some things in the Book of Genesis may be interpreted in a not strictly literal way (without becoming a heretic), the fact that all humans are descendants of Adam cannot be disputed.
Creation of Adam. Image by Lawrence Lew OP, CC-BY-NC-ND 2.0, here