Peace with God means warfare with the enemies of God. Christ made clear that allegiance to Him meant a sword of division (Matt. 10:34-36). In a sinful world, some warfare is inescapable. A man must therefore pick his enemies: God or sinful man? If a man is at peace with sinful men, he is at war with God. Peace in one sector means warfare in another. God alone, however, can give inner peace now, and, finally, world peace through His sovereign law (Micah 4:2).

p. 781 - Writings - The Institutes of Biblical Law (1973)