The thing is, they do not know the name, because their senses are not purified. You cannot understand God by imperfect senses. Therefore Bhāgavata says, ataḥ śrī-kṛṣṇa-nāmadi. Nāmadi. Nāma means name; adi, because name is the beginning of everything. Just like if I want to make friendship with you, I ask you, "What is your name?" That is the beginning. If you go to the court, before beginning the judgment, "What is your name? What is your father's name?" You submit any application, "What is your name?" So nāmadi.
So if we want to understand the Supreme Absolute Truth, we should begin from the name, Kṛṣṇa, Hare Kṛṣṇa, the name, the holy name. But we cannot understand whether this is the name of God, due to our imperfect senses. Therefore the formula is, ataḥ śrī-kṛṣṇa-nāmadi na bhaved grāhyam indriyaiḥ (CC Madhya 17.136). You cannot understand. Just like we are chanting Hare Kṛṣṇa, somebody is taking pleasure in hearing the name of Kṛṣṇa. Somebody may say, "What is this nonsense? They are disturbing," because he has no knowledge of the name.