I agree that way too many people think of the bible as the only authority.
My brother the [devout]JW will argue that the [catholic] church does not follow the bible and that they fell away from Jesus's true teachings by the early 3rd or 4th century. No specific date because the WTS has not given him that info.
When I tell him that the bible is a catholic book that was confirmed around 392 ad, he just has a very confused look.
The early church fathers [and their writings] were and are a treasure. Their teachings are confirmed in 2Thessalonians 2:15
NWT 2Thess 2:15 So, then, brothers, stand firm and maintain ? YOUR ? hold on the traditions that ? YOU ? were taught, whether it was through a verbal message or through a letter of ours