Objection: The theory of evolution is completely compatible with the Catholic faith.
Response: If what you mean by evolution is loosely defined as “change,” then there is little reason to object. However, a more precise definition from the National Association of Biology Teachers reads this way: "The diversity of life on Earth is the outcome of evolution: an unsupervised, impersonal, unpredictable and natural process of temporal descent with genetic modification that is affected by natural selection, chance, historical contingencies and changing environments." An all-natural, unguided and impersonal process is not at all compatible with belief that a personal, supernatural creator God performed these acts ex nihilo (meaning out of nothing). The Magisterium of the Church has permitted debate among Catholics on the subject of evolution within certain defined constraints of revealed truth. These constraints are not widely known because they are either suppressed or ignored by those who favor evolution. A complete listing of these teachings is summarized in the document entitled “What does the Catholic Church teach about origins?” If your belief in evolution causes you to deny any of those teachings from Church Councils and papal encyclicals, then an incompatibility between your faith and evolution exists.