The śāstra says. So it does not mean harer nāma is only Kṛṣṇa. If you have got any other name of Hari, the Supreme Personality of . . . but that name must be actually the name of the Supreme Personality of God, as it is recognized by scriptures.
You may have your own scripture, but if you have got a name sanctioned by the scripture that, "This is the name of God," just like in Jewish scripture they say Jehovah . . . similarly, in Christian scripture, if you have got name . . . just like Buddhists, they have got God, or the Supreme—they accept Lord Buddha.
Similarly, if you have got any other name of the Supreme Lord, you can chant. We are not insisting that you chant Kṛṣṇa. But if you have no specific name of God found in your authentic scripture, then what is the harm if you chant "Kṛṣṇa"? This is not very bad proposal. Any intelligent man . . . if you have, you chant.
Our Lord Caitanya says that nāmnām akāri bahudhā nija-sarva-śaktiḥ, bahudhā nija-sarva . . . tatrārpitā niyamitaḥ . . . (CC Antya 20.16). There are many names. bahudhā As there are many potencies, there are many names also. Just like take for Kṛṣṇa. So Kṛṣṇa is not understood simply by uttering this word "Kṛṣṇa." Kṛṣṇa is understood if you call "Govinda." That is also Kṛṣṇa. If you call "Mādhava," He is also Kṛṣṇa. If you call "Vaṁśī-vadana," He's also Kṛṣṇa. So the aim should be that it is God's name, or the Supreme Lord's name. If the name is different in vibration or form, it does not matter.