Sometime last week I began a conversation with someone who suggested the Catholic faith was equal to Christianity, this person suggested that Catholicism was a denominational equal. As I have grown in my faith I have picked up bits and pieces of understanding in regards to the Catholic faith and can quite honestly say it is a false pagan religion that steals from Christianity to make itself stand tall. All of which is what Jesus has warned about.
After this conversation that lasted through the evening, I chose to look into it a little further and listen to some podcasts by John MacArthur as he explained the heresy of Catholicism. Not only does John do a beautiful job explaining the dangers, but he uses a number of sources in these podcasts. One specifically that stands out to me is the Catholic Doctrine itself.
Here is a collection of John MacArthur's research regarding the Catholic Church.
Book referred to by John MacArthur