A second time Mendelssohn was compelled to emerge from his retirement, and give his views upon religion. This he did in a work entitled "Jerusalem," or "Upon Ecclesiastical Power and Judaism" (spring, 1783), whose purity of contents and form is a memorial of his lofty genius. The gentleness that breathes through this book, the warmth of conviction, the frankness of utterance, its childlike ingenuousness, yet profoundly thoughtful train of ideas, the graceful style which renders even dry discussion enjoyable--all these qualities earned contemporary approval for this work, and will always assure it a place in literature. At the time it excited great surprise. It had been believed, that, owing to his ideas upon religion and Judaism, Mendelssohn, if he had not entirely broken away from Judaism, had yet declared many things therein to be worthless. He now showed that he was an ardent Jew, and would not yield a tittle of existing Judaism, either rabbinical or biblical; that he, in fact, claimed the highest privileges for it. All this was in accord with his peculiar method of thought.
Judaism recognizes the freedom of religious convictions. Original, pure Judaism, therefore, contains no binding articles of belief, no symbolical books, by which the faithful were compelled to swear and affirm their incumbent duty. Judaism prescribes not faith, but knowledge, and it urges that its doctrines be taken to heart. In this despised religion everyone may think, opine, and err as he pleases, without incurring the guilt of heresy. Its right of inflicting punishment begins only when evil thoughts become acts. Why? Because Judaism is not revealed religion, but revealed legislation. Its first precept is not, "thou shalt believe or not believe," but, "thou shalt do or abstain from doing."
"In the divinely-ordained constitution, state and religion are one. Not unbelief, false teaching, and error, but wicked offenses against the principles of the state and the national constitution are chastised. With the destruction of the Temple, _i. e._, with the downfall of the state, all corporal and capital punishment, as well as money fines, ceased. The national bonds were dissolved; religious trespasses were no longer crimes against the state, and religion, as such, knows no punishments."