"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)."
When he nailed his 95 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. Compromise is sometimes a worse evil than division. Second Corinthians 6:14-17 isn't speaking only of marriage when it says,
Therefore, come out from their midst and be separate," says the Lord.