Shake off all fears and servile prejudices under which weak minds are severely crouched. Fix Reason firmly in her seat and call to her tribunal every fact, every opinion. Question with boldness even the existence of a God; because if there be one, he must more approve of the homage of reason rather than of blindfolded fear. You will naturally examine first, the religion of your own country. Read the Bible then as you would Livy or Tacitus. For example in the Book of Joshua we are told that the sun stood still for several hours. Were we to read that fact in Livy or Tacitus, we should class it with their showers of blood, speaking of statues, beasts, etc. But it is said that the writer of that book was inspired. Examine therefore, candidly, what evidence there is of his having been inspired. The pretension is entitled to your inquiry because millions believe it. On the other hand you are astronomer enough to know how contrary it is to the law of nature. … Do not be frightened from this inquiry by any fear of its consequences. If it ends in a belief that there is no God, you will find incitements to virtue in the comfort and pleasantness you will feel in its exercise, and the love of others which it will procure for you. If you find reason to believe there is a God, a consciousness that you are acting under his eye, and that he approves you will be a vast additional incitement: if that Jesus was also a God, you will be comforted by a belief of his aid and love. Your own reason is the only oracle given you by heaven; and you are answerable, not for the rightness but for the uprightness of the decision.
To argue with a man who has renounced the use and authority of reason, and whose philosophy consists in holding humanity in contempt, is like administering medicine to the dead, or endeavoring to convert an atheist by scripture.