Catechism of the Catholic Church
2127 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. In other cases, the agnostic makes no judgment about God's existence, declaring it impossible to prove, or even to affirm or deny.
2128 Agnosticism can sometimes include a certain search for God, but it can equally express indifferentism, a flight from the ultimate question of existence, and a sluggish moral conscience. Agnosticism is all too often equivalent to practical atheism.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.