It is a completely mistaken idea that one can worship Kṛṣṇa in any form or in any way and still attain the ultimate result of receiving the favor of the Lord. This is a decision made by gross materialists. Generally such men say that you can manufacture your own way of worshiping the Supreme Lord and that any type of worship is sufficient to approach the Supreme Personality of Godhead. Certainly there are different means for attaining different results in fruitive activity, speculative knowledge, mystic yoga and austerity. Crude men therefore say that if one adopts any of these methods one achieves the Supreme Personality of Godhead’s favor. They claim that it doesn’t matter what kind of method one adopts. A general example is given: If one wishes to arrive at a certain place, there are many roads leading there, and one can go to that place by any one of these roads. Similarly, these gross materialists say, there are different ways to attain the favor of the Supreme Personality of Godhead. They claim that one can conceive of the Supreme Personality of Godhead as Goddess Durgā, Goddess Kālī, Lord Śiva, Demigod Gaṇeśa, Lord Rāmacandra, Kṛṣṇa, the impersonal Brahman or whatever, and one can chant the Lord’s name in any way and in any form. Such materialists claim that since ultimately all these names and forms are one, the result is the same. They also give the example that a man who has different names will answer if called by any one of them. Therefore, they claim, there is no need to chant the Hare Kṛṣṇa mantra. If one chants the name of Kālī, Durgā, Śiva, Gaṇeśa or anyone else, the result will be the same. Such claims made by mental speculators are no doubt very pleasing to mental speculators, but those who are actually in knowledge do not admit such conclusions, which are against the authority of the śāstras.
Ref >> Srila Prabhupada Vani.