kartāraṁ bhajate so ’pi
na hy akartuḥ prabhur hi saḥ
asti — there is; cet — if hypothetically; īśvaraḥ — a supreme controller; kaścit — someone; phala-rūpī — serving to award fruitive results; anya-karmaṇām — of the activities of other persons; kartāram — the performer of activity; bhajate — depends upon; saḥ — He; api — even; na — not; hi — after all; akartuḥ — of one who performs no activity; prabhuḥ — the master; hi — certainly; saḥ — He.
Even if there is some supreme controller who awards all others the results of their activities, He must also depend upon a performer’s engaging in activity. After all, there is no question of being the bestower of fruitive results unless fruitive activities have actually been performed.
Here Lord Kṛṣṇa argues that if there is a supreme controller, He must depend on a performer of activity to reciprocate with and must therefore also be subject to the laws of karma, being obliged to award happiness and distress to conditioned souls according to the laws of good and evil.
This superficial argument neglects the obvious point that the laws of nature that prescribe the good and bad results of pious and impious acts are themselves creations of the all-good Supreme Lord. Being the creator and sustainer of these laws, the Lord is not subject to them. Furthermore, the Lord is not dependent on the work of the conditioned souls, since He is satisfied and complete within Himself. Out of His all-merciful nature He awards the results appropriate to our activities. That which we call destiny, fate or karma is an elaborate and subtle system of rewards and punishments meant for gradually encouraging conditioned souls to evolve to the stage of perfect consciousness, which is their original, constitutional nature.
The Supreme Personality of Godhead has so dexterously formulated and applied the laws of material nature governing punishment and reward for human behavior that the living being is discouraged from sin and encouraged toward goodness without suffering any significant interference with his free will as an eternal soul.
In contrast to the material nature, the Lord exhibits His essential nature in the spiritual world, where He reciprocates the eternal love of His pure devotees. Such loving affairs are based completely on the mutual freedom of the Lord and His devotees, not on a mechanical reciprocation of coinciding selfish interests. The Supreme Lord, assisted by His pure devotees, repeatedly offers the conditioned souls of this world the opportunity to give up their bizarre attempt at exploiting the material universe and go back home, back to Godhead, for an eternal life of bliss and knowledge. Considering all these points, the atheistic arguments given here by Lord Kṛṣṇa in a playful mood are not to be taken seriously.