I was studying about the Catholic faith when God saved me. I knew immediately that I needed to go to a Bible believing church, because Christ was the center of my faith, not the rites and rituals in the RCC.
I have since that time studied extensively about the Catholic Church and other religions. My grandmother was a born again Orthodox believer. So I also studied the differences between the RCC and the Orthodox church, particularly what caused the split between those two churches a thousand years ago.
Basically, the RCC (Roman Catholic Church) has a lot of extra-biblical doctrines, which are not in the Bible. This goes from Mary being sin free and assumed into heaven, transubstantiation, to salvation only coming from the church, and not knowing if you are good enough till after you die and spend time in purgatory. They also claim these extra-biblical doctrines were given to the RCC only.
Salvation is through Jesus Christ, not a church. A priest does not perform miracles in the mass. The first pope was from Alexandria in the 3rd century BC. That is the first time that the word "pope" was used. Rome then stole it and used it for their bishop.
Oh yes, I don't believe in man-made hierarchies. I just don't see it in the Bible. I could go on, if you want. I am sure some others will chime in.
Although I am totally against many of the doctrines of the RCC, I am not against the people.