How do we know how to be the people God wants us to be? There is a foundation that (most) all people who follow God start with- I don’t want to receive the payment for my sins. From there, the natural progression is to find out how to be right in the sight of God, since He will judge us according to the things that we do (Romans 2.6). So those who want to be righteous (should) begin to check the pages of the Bible to find out what God desires of them. But this is where different denominations begin to splinter in their beliefs and teachings.
It is the belief of (most) of the Churches of Christ that the Bible holds all of the answers to all questions about how to be a righteous person. They (typically) have no external creeds. Creeds are things written that are not found in the Bible, or things they believe the Bible should say in a specific order. Many denominations add something else to the Bible that they also view as authoritative- meaning, rules that should be followed. For example, the Catholic church has a book called a “Catachism” that includes instructions for worship and life. The Mormon church considers the Bible, “the book of Mormon”, a book called “Doctrine and Covenants” and a book called “Pearl of Great Price”, as books that are from God. Typically, every denomination has a book or creed that they view as having authority alongside the Bible.
A few denominations (including those who consider themselves non-denominational) consider that the Bible is a good starting place, but that it needs to be interpretated by someone so that people can get it correct. Meaning, they claim to speak for the Bible, inevitably changing something that the Bible says because they feel it needs “updating” for the modern era. This is the danger I see currently pervading churches who strive to only use the Bible as the complete authority of God. The discussion typically starts with, “it’s just not Christian to…”
What is, and what is not, “Christian” begins and ends with the Bible. There are so many traditions that hide as “Christian” that Jesus never taught, and true churches are in danger of accepting these traditional “Christian” values without authority.