Sola scriptura is the formal principle of the Reformation and is more contested inside Protestantism than outside it: no Protestant body actually reads scripture without a tradition of interpretation, and the magisterial Reformers valued the creeds and the church fathers highly. The claim is about final authority rather than sole source — scripture judges tradition rather than sitting alongside it. Catholic and Orthodox critics have always argued that this guarantees fragmentation, and the count of Protestant denominations is their exhibit.