Martin Luther wasn’t prone to compromise. He famously said in his sermon “Knowledge of God’s Will and Its Fruit”:
The world at the present time is sagaciously discussing how to quell the controversy and strife over doctrine and faith, and how to effect a compromise between the Church and the Papacy. Let the learned, the wise, it is said, bishops, emperor and princes, arbitrate. Each side can easily yield something, and it is better to concede some things which can be construed according to individual interpretation, than that so much persecution, bloodshed, war, and terrible, endless dissension and destruction be permitted.
Here is lack of understanding, for understanding proves by the Word that such patchwork is not according to God’s will, but that doctrine, faith and worship must be preserved pure and unadulterated; there must be no mingling with human nonsense, human opinions or wisdom.
The Scriptures give us this rule: “We must obey God rather than men” (Acts 5:29).
It is interesting to speculate what the church would be like today if Luther had compromised. The pressure was heavy on him to tone down his teaching, soften his message, and stop poking his finger in the eye of the papacy. Even many of his friends and supporters urged Luther to come to terms with Rome for the sake of harmony in the church. Luther himself prayed earnestly that the effect of his teaching would not be divisive.
When he nailed his Ninety-five Theses to the door, the last thing he wanted to do was split the church.
Yet sometimes division is fitting, even healthy, for the church. Especially in times like Luther’s—and like ours—when the visible church seems full of counterfeit Christians, it is right for the true people of God to declare themselves and defend the truth. Compromise is sometimes a worse evil than division. Second Corinthians 6:14-17 isn’t speaking only of marriage when it says:
Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness? Or what harmony has Christ with Satan, or what has a believer in common with an unbeliever? Or what agreement has the temple of God with idols? For we are the temple of the living God; just as God said, “I will dwell in them and walk among them; and I will be their God, and they shall be My people. Therefore, come out from their midst and be separate,” says the Lord.
Sadly, this familiar command to separate is frequently both misunderstood and violated. But Paul is not giving believers license for legalism, sectarianism, or monasticism.
Instead, he’s drawing on an analogy from the Mosaic law. In Deuteronomy 22:10, the Lord commanded the Israelites, “You shall not plow with an ox and a donkey together.” Those two animals do not have the same nature, gait, or strength. Therefore it would be impossible for such a mismatched pair to plow together effectively. They would be unequally yoked.