On the subject of re-incarnation, Shri Nathji used to say:
It is commonly asked whether the founders of all religious faiths were aware of re-incarnation or not. If it existed, it existed for all. But it is mostly in Hinduism and Buddhism that such a concept is dwelled upon. All religious leaders spoke of an after-life and of heaven and hell. If we assume that all these founders were aware of re-incarnation, then we must also assume that many of them did not lay stress on it be¬cause they considered the concept self-defeating. For example, there is a student who is made to sit in an examination. He is told: ‘If you don’t pass now, you will be given another chance, and if you don’t pass even then, you will be given another chance and so on.’ The student will naturally become careless. If not now, then later!’ he will tell himself. No urgency of purpose will seize him. Now take the case of a student who is told: ‘This examination is the one and only one. If you pass, you pass, and if you fail, you fail forever! There will be no second chance!’ The student will do his best to pass.
In a like manner, those who are told of re-incarnation might develop a tendency towards procrastination: ‘O, if not in this life, then we can try in the next!’ Whilst those who are told that this life is the only one that they will ever have, will try to make the best of it. It was, perhaps, for this reason that some founders, who might have been aware of re-incarnation, chose to ignore it, and laid emphasis on this life alone!