11. All religions have proclaimed the principle of the happiness or unhappiness of the soul after death, in other words, the principle of future rewards and punishments, summed up in the doctrinal idea of “Heaven” and “Hell”, which is common to them all. But those religions differ radically as to the nature of the rewards and punishments of the future, and especially as to the conditions upon which they depend. Hence have arisen contradictory beliefs, which have produced various forms of worship, and have led to the imposition of special practices by each of them as a method of honoring God, and thus of gaining admission to “Heaven” and
12. All the religions of the world were necessarily, at their origin, in harmony with the degree of moral and intellectual advancement of the peoples among whom they took their rise, and who, —being still too deeply sunk in materiality to conceive of things purely spiritual—made the greater part of their religious duties to consist in the accomplishment of certain external forms. For a time, forms suffice to satisfy the mind; at a later period, when men acquire more light, they feel the emptiness of those forms, and, if the doctrines of their faith do not suffice to supply the void left by the collapse of its forms, they abandon their religion and become
13. If that primitive formula had always kept pace with the accessional movement of the human mind, the same harmony would always have existed between them, and there would have never been any unbelievers, because the need of believing is natural to the human heart, and men will believe if they are presented with religious ideas in harmony with they intellectual needs. Man would fain know whence he comes and whither he is going; but if that which is set before him as the object of life does not correspond either to his aspirations, to the idea that he has formed to himself of God, or to the data of physical science, —if, moreover, it is sought to impose on him, as necessary to the attainment of that object, conditions of which the utility is not perceived by his reason, —he naturally rejects the whole. Materialism and Pantheism appear to him more rational simply because they reason and discuss. Their reasoning is false, but, at all events, they reason; and he would rather reason falsely than not reason at all.
But let the doctrine of a future life be presented to him under an aspect that is, at once, satisfactory to his reason, and worthy, in all respects, of the greatness, the justice, and the infinite goodness of God, and he will renounce both Materialism and Pantheism, of which every man feels the hollowness in his secret soul, and which are only accepted for lack of something better; and, as Spiritism gives something very much better than those empty and comfortless theories, it is eagerly welcomed by all those who do not find, in the common beliefs and philosophies of the day, the certainty for which they long, and who are consequently undergoing the tortures of doubt. The Spiritist theory is confirmed both by argument and by facts; and it therefore furnishes the broad and solid basis of belief that no other theory is able to supply.
(Book: Heaven and hell – Allan Kardec).