When Sanatana Gosvamin asked Lord Caitanya Mahaprabhu about  svarupa , or the real constitution of the living being, the Lord replied that the real constitution of the entity is to render service to the Lord. Extending this, we see that one being serves another living being in some capacity and thus enjoys its life. An animal serves a man, a friend serves his friend, mother serves child, husband serves wife, Mr. A serves Mr. B, Mr. B serves Mr. C, and so on. There is no exception to service in the society of living beings. The politician convinces the voter of his capacity for service and thus gets his job. The artisan serves the merchant; the store owner serves his customer. In fact, no living being is exempted from rendering service to others. Service, then, is a thing which is the constant companion of the living being, and it can be concluded that rendering service is the eternal religion of the eternal living entity.
When a man claims allegiance to some designated faith or sect, such as Hindu, Buddhist, Muslim, or Christian, this is not eternal. Such faiths can be changed. The Muslim may become a Christian, or the Christian may become a Hindu. Such changeable faith, therefore, is not religion. However, if one be Hindu, Muslim or Christian, one is always a servant. So the particular faith is not the religion, but service is the religion.
We are in a relationship of service to the Supreme Lord. He is the enjoyer, and we are His servants. We are created for His enjoyment, and if we accept that position, it makes us happy. Going back to our earlier example, fingers cannot be independently happy without the cooperation of the stomach. Similarly, the living entity cannot be happy without rendering service to the Supreme Lord.
Worship of demigods is not approved in  Bhagavad-gita  because, in the Seventh Chapter, twenty-eighth verse, the Lord says, "Only those who are cast adrift by lust worship the demigods instead of the Lord."
Now, when we speak of Krsna, we should remember that this is not a sectarian name. Krsna means all pleasure. Krsna, the Supreme Lord, is the reservoir of pleasure. Our consciousness seeks happiness because we are part and parcel of the Lord. The Lord is always happy, and if we dovetail our activities with His, we will partake of His happiness.
The Lord incarnates in order to show us His joyous nature and pastimes. When Krsna was at Vrndavana, His activities with His friends, the cowherd boys, His girl friends, and all His other pastimes were full of happiness. The whole population of