You ought to consider that very, very, very carefully while looking in a mirror. You might also want to look at 2 Pet 2:1-3 while looking in that same mirror.
A wonderful verse, that more RC's should carefully consider.
2 Pet 2:1 But there were also false prophets among the people, just as there will be false teachers among you. They will secretly introduce destructive heresies, even denying the sovereign Lord who bought them—bringing swift destruction on themselves. 2Many will follow their shameful ways and will bring the way of truth into disrepute. 3 In their greed these teachers will exploit you with stories they have made up. Their condemnation has long been hanging over them, and their destruction has not been sleeping.
We have been arguing this very thing. We have been arguing that the one deposit of Faith was given to the Saints for all time and is found in total in the scriptures.
Who is it that introduced New/developed, teaching (Marian doctrine, papal infalibity, purgatory, etc...) into the church, that was most definitely not part of the deposit of Faith given to the Apostles/Saints?