Tim Chester, from his excellent book, You Can Change:
God is using different people, the contrasting personalities, in your church to change your heart. He's using the difficult people, the annoying people, the sinful people. He's placed you together so you can rub off each other's rough edges. It's as if God has put us, like rocks, into a bag and is shaking us about so that we collide with one another. Sometimes sparks fly, but gradually we become beautiful, smooth gemstones.