Sarvaṁ khalv idaṁ brahma means that everything is Lord Kṛṣṇa in the sense that everything is His energy. That is the vision of the mahā-bhāgavatas. They see everything in relation to Kṛṣṇa. The impersonalists argue that Kṛṣṇa Himself has been transformed into many and that therefore everything is Kṛṣṇa and worship of anything is worship of Him. This false argument is answered by Kṛṣṇa in the Bhagavad-gītā: although everything is a transformation of the energy of Kṛṣṇa, He is not present everywhere. He is simultaneously present and not present. By His energy He is present everywhere, but as the energetic He is not present everywhere. This simultaneous presence and nonpresence is inconceivable to our present senses. But a clear explanation is given in the beginning of the Īśopaniṣad, in which it is stated that the Supreme Lord is so complete that although unlimited energies and their transformations emanate from Kṛṣṇa, Kṛṣṇa’s personality is not in the least bit transformed. Therefore, since Kṛṣṇa is the cause of all causes, intelligent persons should take shelter of His lotus feet.
Kṛṣṇa advises everyone just to surrender unto Him alone, and that is the way of Vedic instruction. Since Kṛṣṇa is the cause of all causes, He is worshiped by all kinds of sages and saints through observance of the regulative principles. As far as meditation is concerned, great personalities meditate on the transcendental form of Kṛṣṇa within the heart. In this way the minds of great personalities are always engaged in Kṛṣṇa. With their minds engaged in Kṛṣṇa, naturally the captivated devotees simply talk of Kṛṣṇa.
Talking of Kṛṣṇa or singing of Kṛṣṇa is called kīrtana. Lord Caitanya recommends, kīrtanīyaḥ sadā hariḥ (CC Ādi 17.31), which means always thinking and talking of Kṛṣṇa and nothing else. That is called Kṛṣṇa consciousness. Kṛṣṇa consciousness is so sublime that anyone who takes to this process is elevated to the highest perfection of life—far, far beyond the concept of liberation. In the Bhagavad-gītā, therefore, Kṛṣṇa advises everyone always to think of Him, render devotional service to Him, worship Him and offer obeisances to Him. In this way a devotee becomes fully Kṛṣṇa-ized and, being always situated in Kṛṣṇa consciousness, ultimately goes back to Kṛṣṇa.
Although the Vedas have recommended worship of different demigods as different parts and parcels of Kṛṣṇa, it is to be understood that such instructions are meant for less intelligent men who are still attracted by material sense enjoyment. But the person who actually wants perfect fulfillment of the mission of human life should simply worship Lord Kṛṣṇa, and that will simplify the matter and completely guarantee the success of his human life. Although the sky, the water and the land are all part of the material world, when one stands on the solid land his position is more secure than when he stands in the sky or the water. An intelligent person, therefore, does not stand under the protection of different demigods, although they are part and parcel of Kṛṣṇa. Rather, he stands on the solid ground of Kṛṣṇa consciousness. That makes his position sound and secure.
Impersonalists sometimes give the example that if one stands on a stone or a piece of wood one certainly stands on the surface of the land, because the stone and wood both rest on the surface of the earth. But it may be replied that if one stands directly on the surface of the earth he is more secure than if he stands on the wood or stone, which rest on the earth. In other words, taking shelter of Paramātmā or taking shelter of impersonal Brahman is not as secure a course as taking direct shelter of Kṛṣṇa in Kṛṣṇa consciousness. The position of the jñānīs and yogīs is therefore not as secure as the position of the devotees of Kṛṣṇa. Lord Kṛṣṇa has therefore advised in the Bhagavad-gītā that only a person who has lost his sense takes to the worship of demigods. And regarding persons attached to the impersonal Brahman, Śrīmad-Bhāgavatam says, “My dear Lord, those who think of themselves as liberated by mental speculation are not yet purified of the contamination of material nature because of their inability to find the shelter of Your lotus feet. Although they rise to the transcendental situation of existence in impersonal Brahman, they certainly fall from that exalted position because they deride Your lotus feet.” Lord Kṛṣṇa therefore advises that the worshipers of the demigods are not very intelligent persons because they derive only temporary, exhaustible results. Their endeavors are those of less intelligent men. On the other hand, the Lord assures that His devotee has no fear of falling.