Edited from a lecture by Jagad Guru Siddhaswarupananda Paramahamsa
It is normally taken by people that religion means a type of faith, but this is not actually the real meaning of religion.
In the introduction to the Bhagavad Gita As It Is, A.C. Bhaktivedanta Swami explains very clearly that actually the Sanskrit word 'sanatan-dharma' is a little different from the English word 'religion' in that it better describes what religion actually is. Generally, we think of 'religion' in connection with a particular sect, but 'sanatan-dharma' refers to the eternal function of the eternal living being in relationship with the Supreme Lord. Bhaktivedanta Swami explains:
"The English word religion is a little different from sanatan-dharma. Religion conveys the idea of faith, and faith may change. One may have faith in a particular process, and he may change that faith and adopt another, but sanatan-dharma refers to that activity which cannot be changed. For instance, liquidity cannot be taken from water, nor can heat be taken from fire. Similarly the eternal function of the eternal living entity cannot be taken away from the living entity."
So this means that the constant companion, or eternal quality of the living entity is the living entity's religion.
Firstly we must analyze what part of the living being does not change. We've already described many times how the cells of the gross material body are completely removed at least every 7 years, thus we can conclude that the body is not a person's constant companion because it is always changing. The living entity is not the material body, but is the living force or soul temporarily within the body, the eternal spirit soul. Although the body and mind may change, you are still you. Also anything in connection with the temporary body, any labels that are put on it, must also be considered to be temporary.
For example, a person may profess to belong to a particular faith which is in reference to a certain time and circumstance, but such designations are not sanatan-dharma, or eternal, because they have a beginning and an end. For example, a person may change his faith from Christian to Muslim or he may recall that “I became a Christian on such and such a date,” therefore these designations are simply added labels in connection with the temporary body. They are temporary, external designations because you have taken them on and therefore it is natural to conclude that they will be taken off sooner or later.
So when we are speaking of religion, we are not meaning something artificially placed or superimposed on the living entity. After all, what was there before you started calling yourself a Christian, a Hindu, a Muslim or a Buddhist? What characteristics of your self existed before you started calling yourself any of those things? We've already established that the first quality of the living being is that you are eternal, spirit soul. You cannot take this quality away from yourself any more than you take liquidity from water, or heat from fire. You are in essence the eternal living being.
The second characteristic or tendency of the living being (you can analyze this in yourself) is that the living being is always rendering service and feeling love or affection. You can easily see that every living being is constantly engaged in rendering service to another living being. For example, lower animals serve human beings as servants serve their master. Bhaktivedanta Swami explains:
"It can be seen that there is no exception in the society of living beings to the activity of service. The politician presents his manifesto for the public to convince them of his capacity for service. The voters therefore give the politician their valuable votes, thinking that he will render valuable service to society. The shop-keeper serves the customer, and the artisan serves the capitalist. The capitalist serves the family, and the family serves the state in the terms of the eternal capacity of the eternal living being. In this way we can see that no living being is exempt from rendering service to other living beings, and therefore we can safely conclude that service is the constant companion of the living being and that the rendering of service is the eternal religion of the living entity."
The point is that if you are eternal by nature and your eternal function is to love and serve someone then obviously your activities should be in connection with the Supreme Eternal Living Being, beyond the bodily conception of life. “I am Hindu, I'm this, I'm that.” If you can stop being a Christian or a Hindu or if you can become a Christian or a Hindu, then that is not actually religion because it is not eternal.
Actually the different faiths are ultimately meant to wake a person up to his actual, religious condition. In other words, whatever process one may be following―the Christian faith, the Hindu faith, whatever it may be, if it doesn't have the effect of bringing a person to the platform of understanding his eternal identity as spirit soul and his eternal relationship with the Supreme soul, then it has no meaning. This is because instead of helping a person come to the platform of actual religion, namely love of God, the person begins to identify his particular faith as religion itself. So to become a religious person does not mean that “I'm a Hindu, I'm a Christian, I've joined this ream, I've joined that team.” but it means to uncover what is already there, your personal eternal loving relationship with God, beyond all sectarianism and fanaticism.
So all of this fighting, this party or sectarian spirit is described by Bhaktivinode Thakur as 'the greatest enemy of mankind'. If someone thinks ‘”I'm a Christian,” he'll be considering Moslems or Hindus to be his enemy and vice versa. Such divisions have nothing to do with real religion but are based on false bodily identification. There are so many similarly based conflicts and religious wars; for example, why do the blacks and whites fight? Why do they think there is any difference? Because they are only seeing with their material eyes. They do not see with the spiritual eye, that within the black body and white body are both the children of God. If people were thinking 'I am spirit soul, you are spirit soul' there would be no question of conflict.
But despite all the talk of religion, the vast majority are actually following the faith of materialism, identification with the external body, regardless of what they may call themselves.
Ex-president Jimmy Carter, supposedly a Christian, once made a statement that is indicative of this limited kind of vision. He said something like, “the Egyptians and Jews are all right, I really feel close to them because after all we worship the same God, the God of Abraham.” So indirectly he was saying that there must be other Gods because we worship the same God. In other words, he couldn't feel close to some other people because they worship another God. But actually God is the Father of all living beings, not just the Father of some nations or one religious faith.
So Lord Chaitanya has appeared to teach us what is real religion, i.e. we are not actually these material bodies but we are actually eternal parts and parcels of the Supreme Person and by nature we are meant to love and serve Him. Lord Chaitanya stated that in this age of chaos and confusion, where everybody is bickering due to party spirit, the only way to go beyond all this is to congregate and sing the names of the Supreme Lord, He further states:
"Oh my Lord, You have hundreds and millions of names and each of Your Holy Names is invested with transcendental power."
So although God is one, He has many names which are based on His different qualities. For example, God is called Jehovah because God is all-powerful. God is called Allah, meaning all-compassionate. And He is called Krishna, the all-attractive Person. So you may call God by one name or different names but that doesn't mean there is another God. This is a misunderstanding which leads to so much fighting.
The first point of religion is that you must understand that you are not the body. You are the spirit soul within the body. As soon as you understand this, you will immediately realize that you are not white or black, American or Russian, Christian or Hindu, or any external designation. The second is that your position is dominated. You are not the Supreme spirit, you are part and parcel of the Supreme. This brings you to the third point, your natural function, which is engaging in His loving service.
Krishna states at the end of the Bhagavad-gita:
"Give up all varieties of religion and just surrender unto (love) Me."
So somehow try to develop your love for God. This is the real meaning of religion.