What Is Rc Religion?

That would be Roman Catholicism. Despite what you might have read in rather loud print elsewhere, the main difference between Catholics and Protestants is that Protestants accord Mary no particular significance other than having been the mother of Jesus.

There are many differences between Roman Catholicism and other forms of Christianity.  One of the major ones is that Catholics believe that the Eucharist is the body of Christ, not just a symbol.  Also, we do believe in the Trinity and acknowledge all 3 persons of God.