Catechism of the Catholic Church §194 — excerpt
The Apostles' Creed is so called because it is rightly considered to be a faithful summary of the apostles' faith. It is the ancient baptismal symbol of the Church of Rome.
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.
Also cites: St. Ambrose, Expl. symb. 7: PL 17, 1196