“Worldly government has laws which extend no farther than to life and property and what is external upon earth. For over the soul God can and will let no one rule but Himself. Therefore, where temporal power presumes to prescribe laws for the soul, it encroaches upon God’s government and only misleads and destroys the souls.”
“But the thoughts and intents of the heart can be known to no one but God; therefore it is useless and impossible to command or compel any one by force to believe one thing or another… Since, then, belief or unbelief is a matter of every one’s conscience, and since this is no lessening of the secular power, the latter should be content and attend to its own affairs and permit men to believe one thing or another, as they are able and willing, and constrain no one by force… Hence arise the well-known saying, found also in Augustine, ‘No one can or ought to be constrained to believe.”
“If then your prince or temporal lord commands you to…believe this or that, or commands you to give up certain books, you should say, It does not befit Lucifer to sit by the side of God. Dear Lord, I owe you obedience with life and goods; command me within the limits of your power on earth, and I will obey. But if you command me to believe, and to put away books, I will not obey; for in this case you are a tyrant and overreach yourself, and command where you have neither right nor power, etc. Should he take your property for this, and punish such disobedience, blessed are you. Thank God that you are worthy to suffer for the sake of the divine Word, and let him rave, fool that he is [1 Pet. 4:14; 16; Acts 5:41]. He will meet his judge. For I tell you, if you do not resist him, but give way. and let him take your faith or your books, you have really denied God.”
– excerpts from Martin Luther’s Secular Authority