Jesus said that He didn't come for those who were well, but those who were sick. A church may have many patients, all in different stages of recovery. Some are in terminal or critical condition, others are nearly well, and there are those who have recovered enough to join with the hospital staff in helping to care for the other patients. Ironically, the imperfections in other believers actually serve a helpful purpose to us. Our close-knit fellowship acts as sandpaper that will smooth out our rough edges.
Conflict is necessary to refine spiritual character.
This is the same way our muscular tissue grows strong, by exercising against resistance. The church is like a spiritual gymnasium for believers to practice their love toward others, who are sometimes less than lovable. Applying spiritual virtues against resistance is what makes us grow strong. Therefore, the weak ones in our midst need our love and ministry, and we need them in order to grow mature in our love and patience. It's remarkable how we are able to see our true spiritual condition through the reflection of our brethren.