“The one who states his case first seems right, until the other comes and examines him.” (ESV)
When we are on our own, our ideas almost always seem great. We can convince ourselves of anything. This does not, however, mean our ideas are always good. In fact, if we are thinking entirely on our own, the likelihood that we are thinking off track runs pretty high.
We need a community around us to help make sure we are not running off the rails into trouble. This applies in several different areas. When it comes to politics, if we only ever listen to people who agree with us, the sound of our own voice can get awfully loud. We need to regularly listen to and engage with people with whom we do not agree. And this not just to have our own ideas confirmed, but also to consider well what they are saying to see if we need to adapt our ideas some. In order to do this, we need to listen, not just to the cranks on the other side, but to their most reasonable and eloquent promoters.
It applies to theology and reading the Scriptures as well. Too many heresies and cults have come from one person reading the Scriptures incorrectly by himself and building a whole theological system based on the error. We need to read in community, allowing others to evaluate and offer critiques of our ideas. This will help keep us on the right track. This is why we need the church.