Apologetics is the science of the defense and explanation of Christian religion. It is the comprehensive, scientific vindication of the grounds of Christian, Catholic belief, in which the calm, impersonal presentation of underlying principles is of paramount importance, the refutation of objections being added by way of corollary. It addresses itself not to the hostile opponent for the purpose of refutation, but rather to the inquiring mind by way of information. Its aim is to give a scientific presentation of the claims which Christ's revealed religion has on the assent of every rational mind; it seeks to lead the inquirer after truth to recognize, first, the reasonableness and trustworthiness of the Christian revelation as realized in the Catholic Church, and secondly, the corresponding obligation of accepting it. While not compelling faith -- for the certitude it offers is not absolute, but moral -- it shows that the credentials of the Christian religion amply suffice to vindicate the act of faith as a rational act, and to discredit the estrangement of the sceptic and unbeliever as unwarranted and culpable. Its last word is the answer to the question: Why should I be a Catholic? Apologetics thus leads up to Catholic faith, to the acceptance of the Catholic Church as the divinely authorized organ for preserving and rendering efficacious the saving truths revealed by Christ. This is the great fundamental dogma on which all other dogmas rest.