In parallel with the common idea of a Church under siege in the sec. XIX, the presence of dynamism and creativity in its interior is noted. We present something of the Catholic apologetics of the time, which then had one more liberal face, accentuating the developments of science and the facts that it provides in a sure way, and another face that highlights the doctrinal and mysterious part of Christianity. We start with the figure of Lamennais and his disciples. They criticized the forms of certainty of human reasoning based on the thinking subject, thus demanding a criterion of authority represented, for example, by the Pope s word and general reason – all true science would be Catholic. As the century progressed, other currents showed something different. Catholic science was now presented alongside others, implying a true science and a false science, the former consisting of proven truths and therefore compatible with the Catholic faith. A third current highlighted autonomy between science and faith, as in Providentissimus Deus 42. It also shows how this tension between currents occurs in several French encyclopedias of the time, as well as the controversies that occurred in other countries, such as Germany and England.