Srila Prabhupada describes the word ‘HINDU’ from cultural point of view not religious point of view

Hindu means the culture of the Indians. India happens to be situated on the other side of the Indus River which is now in Pakistan which is spelled Indus — in Sanskrit it is called Sindhu. The sindhu was misspelled by the Europeans as Indus, and from Indus the word “Indian” has come. Similarly the Arabians used to pronounce sindus as Hindus. This Hindus is spoken as Hindus. It is neither a Sanskrit word nor is it found in the Vedic literatures. But the culture of the Indians or the Hindus is Vedic and beginning with the four varnas and four asramas. So these four varnas and four asramas are meant for the really civilized human race. Therefore the conclusion is actually when a human being is civilized in the true sense of the term he follows the system of varna and asrama and then he can be called a “Hindu.” Our Krsna Consciousness Movement is preaching these four varnas and four asramas, so naturally it has got some relationship with the Hindus. So Hindus can be understood from the cultural point of view, not a religious point of view. Culture is never religion. Religion is a faith, and culture is educational or advancement of knowledge.

(Letter to: Janmanjaya, Taradevi — Los Angeles 9 July, 1970)

Prabhupāda: So therefore it is very difficult to get their cooperation. Their mentality is, they don’t want to understand this Kṛṣṇa philosophy. They want to remain Hindu. Hindu means hodgepodge, that’s all. Hindu means hodgepodge. Hindu means Śaṅkara philosophy. Yes, that God has no form, and you can imagine any form and worship for your material benefit. This is at the present moment. And we said that we are not Hindus. Hindu is a Muhammadan title, given. Hindu, there is no such word in the Vedic literature. You won’t find this word in Bhagavata, or Bhagavad-gita. The Muhammadans outside India, they used to call the sindhus, sindhu. There is a river, Sindhu river. From Sindhu to Hindu. They cannot speak “s,” they call “ha.” In this way it is a hodgepodge word, but it has come that Vedic followers as “hindus,” but this word is not found in any authorized scripture, no. Our culture is varnasrama-dharma.

(Room Conversation — August 7, 1971, London)