Read: Matthew 5:21-26
So if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there before the altar and go. First be reconciled to your brother, and then come and offer your gift. (Matthew 5:23, 24 ESV)
Have you ever had a really bad argument with someone? What about one that ended so badly you felt really distant at the end of it? Some things happen between people that drive an unhealthy wedge-like space into the relationship.
During his Sermon on the Mount Jesus told his followers that in order to worship to their fullest potential they didn't to do so without any unreconciled relationships. Whoa! It makes sense if you think about it. Why? Because the thing that creates unreconciled hearts is sin.
Sin separated us from God. Jesus came to bring reconciliation to that relationship. But he also came so that we could be reconciled to one another. Further, he expects that of us if we are going to worship him. And while disagreement or discord may sometimes be incredibly difficult to avoid, we should always yearn for reconciliation. It might not come in the way that we would hope for, but God knows our hearts.