What causes quarrels and what causes fights among you?
Is it not this, that your passions are at war within you? You desire and do not have, so you murder. You covet and cannot obtain, so you fight and quarrel. You do not have, because you do not ask.
(James 4:1-2 ESV)
Unfortunately as Christians we aren't perfect, yet. Because of this, we tend to fight and argue on a seemingly daily basis (many times stupid things). Those who don't want anything to do with the church will bring this up and rub it in our face. They have a hard time seeing Jesus or the church as loving when the people who are a part of it don't even get along. We aren't known by our love as Jesus said we should be (John 13:35).
We should each read James 4:1-2 humbly to see why we are fighting. The reason we fight is because of the warring passions inside of us. It is our desires that are causing the problems. Instead of blaming somebody else for starting the fight, look inside yourself and see if it is you who is really the problem. It can be hard to admit our pridefulness. It isn't easy for anyone. If we do this more, we will stop worrying about ourselves so often and love each other more as true disciples of Jesus.
Examine your motive for a recent dispute with another Christian.