In the Bhagavad-gītā we understand about Kṛṣṇa. Bhagavad-gītā is a well-read book all over the world. In any country you will find edition of Bhagavad-gītā by the language of the country. So in this Bhagavad-gītā we find that Kṛṣṇa is giving instruction about what is dharma, religion. He says . . . and at the end of His instruction He says, sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja (BG 18.66) that, "You give up other types of so-called religious principles. You simply surrender unto Me."
So in another place in the Śrīmad-Bhāgavatam it is said, dharmaṁ tu sākṣād bhagavat-praṇītam (SB 6.3.19): "Religion means the codes of God." Just like the state gives us some rules and regulation to live, and one who follows the rules and regulation or the laws of the state, he is called good citizen, and those who do not follow, they are called outlaws or rogues or so many things. Similarly, religion is very simple thing. It is not cumbrous. Simple thing.
If we take it simply, religion means . . . our definition of religion is to accept the orders of God. That's all. It doesn't matter what religion you are following. You may be Christian, I may be Hindu, that may be Muhammadan, but the test of religion is how one has developed his God consciousness. That is the definition given in the Śrīmad-Bhāgavatam. Sa vai puṁsāṁ paro dharmaḥ. There are different types of religion, but the best of them . . . sa vai puṁsāṁ paro. Para means superior, the best. Sa vai puṁsāṁ paro dharmo yato bhaktir adhokṣaje (SB 1.2.6). Adhokṣaje. Adhokṣaja is another description of God. Adha, "where material senses cannot reach." Adhokṣaja. Direct experimental knowledge cannot know God.