Since the Qur'an wasn't all so sweet, I'm doing the much-easier-to-expose Roman Catholic Church. As you probably know, It's the one with the Pope.
To make it short, it shouldn't even be called a branch of Christianity. They say stuff like, "The church is the universal sacrament of salvation", and "Non Christians can be saved through the church", when the Bible says "Believe on the Lord Jesus Christ, and thou shalt be saved."
Along with crazy things like "The Eucharist is most important in the life of the Church because it is Jesus Christ. It is the Incarnation continued in space and time.", and "The Eucharist is a sacrament which really, truly, and substantially contains the body and blood, soul, and divinity of our Lord Jesus Christ under the appearances of bread and wine. It is the great sacrament of God's love in which Christ is eaten...", when the Bible says "Thou shalt not make unto thee any graven image".
Hope this was better than the Qur'an.