Catechism of the Catholic Church §2506 — excerpt
The Christian is not to "be ashamed of testifying to our Lord" (2 Tim 1:8) in deed and word. Martyrdom is the supreme witness given to the truth of the faith.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.