Let there be one mantra for the whole world — the maha-mantra: In this present day, man is very eager to have one scripture, one God, one religion, and one occupation. So let there be one common scripture for the whole world — Bhagavad-gita. And let there be one God only for the whole world — Sri Krsna. And one mantra only — Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare / Hare Rama, Hare Rama, Rama Rama, Hare Hare. And let there be one work only — the service of the Supreme Personality of Godhead.

Srila Prabhupada, Bhagavad-gita As It Is Intro