they weren't "the bible". it was not viewed as you view it, that is, infallible words of god. most protestants don't even know the epistles are just letters written from the apostles from a distance to the real, physical churches they personally founded. it is no surprise that most of these epistles contain admonition to guide the churches the apostles founded into conformity of belief. because it is one church. that one church canonized the bible you refer to today.
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