All practicing Catholics believe. There are lots of non-practicing Catholics; in the US, former Catholics are the 2nd largest denomination. Also it depends what you mean by "believe". We do not believe the following: "once saved always saved", double predestination, "no creed but Christ", that Mary was the mother of God the Father, *sola scriptura*, *sola fide*. We *do* believe in the Apostle's and Nicene Creed, the marriage of Scripture and Tradition, that Mary was the Mother of God Incarnate, and that Jesus was being literal in John 6.