Think about it. There’s nothing preventing a group of people from gathering together and calling themselves a church, is there? What if that group of people really didn’t even believe Jesus was the Savior of the world? What if that group of people wanted to call themselves a church, but didn’t believe anything in the Bible was true? What would stop them from calling themselves a church? Nothing.
So how, then, do we know whether a church is really a church? Or whether a Christian is really a Christian?