14. The belief in a future life is instinctive in the human mind; but, as men have hitherto possessed no clear and sufficient ground for this belief, their imagination has engendered the various religious systems that have given rise to the wide diversities of human worship. As the Spiritist doctrine of the future life is not a work
of imagination more or less ingeniously conceived, but is, on the contrary, deduced from, and confirmed by, the observation of physical facts that are now occurring under our eyes, it will continue to attract, as it has hitherto done, those whose convictions, on this most momentous of subjects, are divergent or unsettled, and will
gradually establish a unitary belief in regard to it; a belief that will be based, no longer on a mere hypothesis, but on a certainty. This unification of human conviction, in regard to the future existence of the soul, will be the first step towards the unification of the forms of worship; it will thus exercise a most important and decisive influence on all the various religions of the world, and will lead, first, to their mutual toleration of one another, and, eventually, to their fusion.
(Book: Heaven and hell – Allan Kardec).