In reading a letter of John Newton I came across this gem:
…he could remove every prejudice, and give equal degrees of light to all his people, so that there should be no difference among them either about doctrine or discipline. But were this the case, their uniformity would not afford them such opportunities of approving their obedience to him, and their love to each other, as they may draw from lesser differences. But alas! remaining corruptions, and the subtlety of Satan, operate so strongly, that the sheep of Christ think they do Him service, by worrying and tearing one another.
In other words, while we are still living on this side of a Redeemed Eden one of the reasons that the Lord continues to allow differences amongst us is to give us an opportunity for love and obedience to Him.
Newton then gives a horribly wonderful example of our tearing at one another in the name of defending the cause of God.
Alas, when self fights in holy armour, and the cause of our own unsanctified passions is honoured with the specious name of the cause of God and truth, then religious zeal is seen in all the sense the original bears but the good sense, and breathes forth indignation, envy, and wrath. Then Satan is transformed into an angel of light, and men suppose themselves to be men abounding in duty, in proportion as they depart from the spirit of love, which is the chief criterion and characteristic of the religion of Jesus.
And now the illustration:
I remember a passage somewhere in ancient history, of a battle fought in the night; both parties were resolute, many were the slain and wounded on both sides, both congratulated themselves on the mischief they had done to their opponents—at length the day broke, and turned their joy into sorrow. They then found to their confusion that their animosity had been wholly owing to fighting in the dark before they had made proper inquiry, for though they had mistaken each other for enemies, they were friends and allies, engaged in the same cause, and had been weakening each other for the advantage of the common enemy.
May we not bruise one another and strike the heel of our common Master whilst thinking that we are in the business of crushing the head of the Serpent.