 If I'm tempted to speak wrongly of someone, God's Word addresses that. It changes my mind about that. If I fail, God's Word shows me the complete forgiveness I have in Christ if I confess my sin and forsake it. Christ shares His truth to us, and when we think the same way, we will have unity. And there will be joy in that. Plain and simple, biblical unity is based on a true understanding and submission to the Word of God and the God of the Word. That's it.