Protestants argue that the scriptures are guaranteed to remain true to their divine source—and thus, only insofar as the church retains scriptural faith is it assured of God's favour. They further assert that, if the church were to fall away from faith through scripture (a possibility Roman Catholics deny but Protestants affirm), its authority would be negated. Therefore, early Protestants argued for eliminating traditions and doctrines they believed were based on distortions of scripture, or were contrary to the Bible—but that the Roman Catholic Church considered scripturally-based aspects of the Christian faith, such as transubstantiation , the doctrine of purgatory , the veneration of images or icons , and especially the doctrine that the Pope in Rome is the head of the church on earth (Papal supremacy) .