So, what's a Christian? One way of defining a Christian is to call him a believer. He is someone who believes that Jesus is the Savior. And, obviously, that's an accurate description - or, at least, it could be. But the way folk think today, 'believing' is something that you can do sitting down. It's merely mental. I believe that 2+2 = 4. I believe that there are 5,280 feet in a mile. I believe that Jesus is the Savior.
These days I'm thinking 'disciple' is a better way of defining what a Christian is. You can't do that sitting down. It requires some action. To be sure, there is a mental aspect to it. There are things that you need to think about, things like the Gospel. Isn't that what much of those New Testament letters were about? 'Here are some things about the Gospel that, maybe, you hadn't thought about.' And once the thinking happens, then the doing follows. Being a disciple of Jesus is something that you do. And so, it's something people can see in action. And people need to see disciples in action. They're too used to watching 'believers' who just 'believe' and then act like everyone else. They need to see disciples. Then, just maybe, they'd be interested in hearing how they might also become disciples of Jesus.