Catechism of the Catholic Church §2127 — excerpt
Agnosticism assumes a number of forms. In certain cases the agnostic refrains from denying God; instead he postulates the existence of a transcendent being which is incapable of revealing itself, and about which nothing can be said.
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.