Although the strength of the devotee's devotion and faith for any God or object is due entirely to the Supreme Self, no matter if the faith be foolish and the God false, yet the reward obtained is said to be temporary, transitory, sure to come to an end. But unlike Western religious systems this is declared to be a matter of law instead of being determined by sentiment or arbitrarily. The sentences in which I find this are as follows:
But the reward of such short-sighted man is temporary. Those who worship the Gods go to the Gods, and those who worship me come to me.
Man, made of thought, occupant only of many bodies from time to time, is eternally thinking. His chains are through thought, his release due to nothing else. His mind is immediately tinted or altered by whatever object it is directed to. By this means the soul is enmeshed in the same thought or series of thoughts as is the mind. If the object be anything that is distinct from the Supreme Self then the mind is at once turned into that, becomes that, is tinted like that. This is one of the natural capacities of the mind. It is naturally clear and uncolored, as we would see if we were able to find one that had not gone through too many experiences. It is moveable and quick, having a disposition to bound from one point to another. Several words would describe it. Chameleon-like it changes color, sponge like it absorbs that to which is applied, sieve-like it at once loses its former color and shape the moment a different object is taken up. Thus, full of joy from an appropriate cause, it may suddenly become gloomy or morose upon the approach of that which is sorrowful or gloomy. We can therefore say it becomes that to which it is devoted.
Now "the Gods" here represent not only the idols of idol-worshipers, but all the objects and desires people run after, for the idols are but the representatives of the desired object. But all these Gods are transitory. If we admit the existence of Indra or any other God, even he is impermanent. Elsewhere it is said that all the Gods are subject to the law of death and rebirth — at the time of the great dissolution they disappear. The vain things which men fix their minds on and run after are of the most illusory and transitory character. So whether it be the imaginary Gods or the desires and objects the mind is fixed on, it — that is, those who thus act — has only a temporary reward because the object taken is in itself temporary. This is law and not sentiment.
Pushing into details a little further it is said that after death the person, compelled thereto by the thoughts of life, becomes fixed in this, that or the other object or state. That is why the intermediate condition of kama-loka is a necessity. In that state they become what they thought. They were bigots and tortured others: those thoughts give them torture. Internal fires consume them until they are purified. The varieties of their different conditions and appearances are as vast in number as are all the immense varieties of thoughts. I could not describe them.
But those who worship or believe in the Self as all-in-all, not separate from any, supreme, the container, the whole, go to It, and, becoming It, know all because of its knowledge, and cease to be subject to change because It is changeless. This also is law, and not sentiment.
The chapter concludes by showing how the ignorant who believe in a Supreme Being with a form, fall into error and darkness at the time of their birth because of the hold which former life-recollections have upon the mind. This includes the power of the Skandhas or aggregates of sensations and desires accumulated in prior lives. At birth these, being a natural part of us, rush to us and we to them, so that a new union is made for another lifetime. In the other life, not having viewed the Self as all and in all, and having worshipped many Gods, the sensations of liking and disliking are so strong that the darkness of rebirth is irresistible. But the wise man died out of his former life with a full knowledge of the Self at the hour of death, and thus prevented the imprinting upon his nature of a set of sensations and desires that would otherwise, upon reincarnation, lead him into error. This is the chapter on Unity, teaching that the Self is all, or if you like the word better, God: that God is all and not outside of nature, and that we must recognize this great unity of all things and beings in the Self. It and the next chapter are on the same subject and are only divided by a question put to Arjuna.