With reference to the above concept of sanātana-dharma we may try to understand the concept of religion from the Sanskrit root meaning of the word dharma. It means that which is constantly with the particular object. As we have already mentioned, when we speak of fire it is concluded at the same time that there is heat and light along with the fire. Without heat and without light, there is no meaning of the word fire. Similarly, we must find out the essential part of a living being which is always companion with him. That part of constant companion of the living being is his eternal quality, and the eternal part of the living being's quality is his eternal religion. When Sanātana Gosvāmī asked Lord Śrī Caitanya Mahāprabhu about the svarūpa—we have already discussed about the svarūpa of every living being—svarūpa or real constitution of the living being, the Lord replied that the constitutional position of the living being is to render service to the Supreme Personality of Godhead. But if we analyze this part of the statement of Lord Caitanya, we can very well see that every living being is constantly engaged in the business of rendering service to another living being. A living being serves another living being in different capacities, and by doing so, the living entity enjoys life. A lower animal serves a human being, a servant serves his master, A serves B master, B serves C master, and C serves D master, and so on. Under the circumstances, we can see that a friend serves another friend, and the mother serves the son, or the wife serves the husband, or husband serves the wife. If we go on searching in that spirit, it will be seen that there is no exception in the society of the living being where we do not find the activity of service. The politician present his manifesto before the public and convinces voters about his service capacity. The voter also gives the politician his valuable vote on expectation that the politician will give service to the society. The shopkeeper serves the customer and the artisan serves the capitalist. The capitalist serves his family and the family serves the head man in terms of the eternal capacity of eternal being. In this way we can see no living being is exempted from the practice of rendering service to other living being, and therefore we can conclude that service is a thing which is the constant companion of the living being, and therefore it may be safely concluded that rendering of service by a living being is the eternal religion of the living being.
When a man professes to belong to a particular type of faith with reference to the particular time and circumstances of birth, and thus one claims to be a Hindu, a Muslim, a Christian, Buddhist, or any other sect, and sub-sect, such designations are non-sanātana-dharma. A Hindu may change his faith to become a Muslim, or a Muslim may change his faith to become a Hindu or a Christian, etc., but in all circumstances such change of religious faith does not allow a person to change his eternal engagement of rendering service to other. A Hindu or a Muslim or a Christian, in all circumstances, he is servant of somebody, and thus to profess a particular type of faith is not to be considered as sanātana-dharma, but the constant companion of the living being, that is, rendering of service, is the sanātana-dharma. So factually, we are related in the service relationship with the Supreme Lord. The Supreme Lord is the supreme enjoyer, and we living entities are eternally His supreme servitors. We are created for His enjoyment, and if we partake, participate in that eternal enjoyment with the Supreme Personality of Godhead, that makes us happy, not otherwise. Independently, as we have already explained that independently, any part of the body, the hand, the feet, the fingers, or any part of the body, independently, cannot be happy without cooperation with the stomach, similarly, the living entity can never be happy without rendering his transcendental loving service to the Supreme Lord. Now, in the Bhagavad-gītā the worship of different demigods is not approved, is not approved because... It is said in the (Bhagavad-gītā seventh chapter, twentieth verse), the Lord says, kāmais tais tair hṛta-jñānāḥ prapadyante 'nya-devatāḥ (BG 7.20). Kāmais tais tair hṛta-jñānāḥ. Those who are directed by lust, only they worship the demigods other than the Supreme Lord, Kṛṣṇa.