"Our happiness in this life is thus, upon many occasions, dependent upon the humble hope and expectation of a life to comea hope and expectation deeply rooted in human nature, which can alone support its lofty ideas of its own dignity, can alone illumine the dreary prospect of its continually approaching mortality, and maintain its cheerfulness under all the heaviest calamities to which, from the disorders of this life, it may sometimes be exposed. That there is a world to come, where exact justice will be done to every man.... is a doctrine, in every respect so venerable, so comfortable to the weakness, so flattering to the grandeur of human nature, that the virtuous man who has the misfortune to doubt of it can- not possibly avoid wishing most earnestly and anxiously to believe it."This doctrine, Adam Smith thinks, could never have fallen into disrepute, had not a doctrine been asserted of a future distribution of rewards and punishments, at total variance with all our moral sentiments. The preference of assiduous flattery to merit or service, which is regarded as the greatest reproach even to the weakness of earthly sovereigns, is often ascribed to divine perfection; "and the duties of devotion, the public and private worship of the Deity, have been represented, even by men of virtue and abilities, as the sole virtues which can either entitle to reward, or exempt from punishment, in the life to come."There is the same absurdity in the notion, which had even its advocate in a philosopher like Massillon, that one hour or day spent in the mortifications of a monastery has more merit in the eye of God than a whole life spent honourably in the profession of a soldier. Such a doctrine is surely contrary to all our moral sentiments, and the principles by which we have been taught by nature to regulate our admiration or contempt. "It is this spirit, however, which, while it has reserved the celestial regions for monks and friars, or for those whose conduct or conversation resembled those of monks and friars, has condemned to the infernal all the heroes, all the statesmen and lawyers, all the poets and philosophers of former ages; all those who have invented, improved, or excelled in the arts which contribute to the subsistence, to the conveniency, or to the ornament of life; all the great protectors, instructors, and benefactors of mankind; all those to whom our natural sense of praiseworthiness forces us to ascribe the highest merit and the most exalted virtue. Can we wonder that so strange an application of this most respectable doctrine should sometimes have exposed it to derision and contempt?"Although, then, Adam Smith considers that reason corroborates the teaching of natural religion regarding the existence of God and the life hereafter, he nowhere recognizes any moral obligation in the belief of one or the other; and they occupy in his system a very similar position to that which they occupy in Kant's, who treats the belief in the existence of God and in immortality as Postulates of the Practical Reason, that is to say, as assumptions morally necessary, however incapable of speculative proof.
Adam Smith, however, does not approach either subject at all from the speculative side, but confines himself entirely to the moral basis of both, to the arguments in their favour which the moral phenomena of life afford, such as have been already indicated.
But besides the argument in favour of the existence of God derived from our moral sentiments, the only argument he employs is derived, not from the logical inconceivability of a contrary belief, but from the incompatibility of such a contrary belief with the happiness of the man so believing. Aman of universal benevolence or boundless goodwill can enjoy no solid happiness unless he is convinced that all the inhabitants of the universe are under the immediate care of that all-wise Being, who directs all the movements of nature, and who is compelled, by His own unalterable perfections, to maintain in it at all times the greatest possible quantity of happiness.