Of course, God is the infallible authority. But God insisted on ONE truth and made sure the books in the Bible and his spoken words and acts that were not written, were preserved as ONE truth and so He founded ONE Church that instructs ONE credo for all generations and all peoples.
Christ didn't found a "church" Steelfish. In Matthew 16:18 He used the word ekklēsian. The word properly means those who are called out of the world and to God. Not once in all of scripture is the concept of an organized hierarchical organization ever taught. Until people understand what the word really meant the corrupt understanding the Catholic Church has created will keep them from understanding what Christ was talking about.
The ONE truth is found in scripture. The Catholic Church perversion of that truth is atrocious.