“I appeal to you, brothers, to watch out for those who cause divisions and create obstacles contrary to the doctrine that you have been taught; avoid them. For such persons do not serve our Lord Christ, but their own appetites, and by smooth talk and flattery they deceive the hearts of the naive.” (ESV – read the chapter)
When it comes to non-Christians, the church is to be open to all people. We should receive with grace and gladness anyone who is interested in becoming a follower of Jesus regardless of their background or what they’ve done.
In the church and among people who claim to be followers of Jesus the story changes somewhat. Oftentimes today, people who are most concerned with protecting the purity and unity of the church work to keep out the world. In the New Testament, the exact opposite approach is taken. The biggest threats to the purity and unity of the church are never from without, but rather within.
The Nexus 