The catechisms of Peter Canisius highlight the struggle within the Catholic Church to reframe Christian identity after the Protestant Reformation. In contrast to the defensive catechesis of Rome, Canisius's catechisms proposed to achieve orthodoxy by encouraging Christian piety.

Still considered essential reading for serious thinkers on religion more than a century and a half after it was written, this seminal work of modern theology, first published in 1845, presents a history of Catholic doctrine from the days of the Apostles to the time of its writing, and follows with specific examples of how the doctrine has not only survived corruption but grown stronger through defending itself against it, and is, therefore, the true religion. This classic of Christian apologetics, considered a foundational work of 19th-century intellectualism on par with Darwin's Origin of Species, is must reading not only for the faithful but also for anyone who wishes to be well educated in the fundamentals of modern thought.