The Krishna consciousness movement is chiefly engaged in chanting the maha-mantra all over the world. Sri Caitanya Mahaprabhu introduced the congregational chanting of the Hare Krishna mantra to give everyone a chance to hear Krishna’s holy name, for simply by hearing Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare, one becomes purified (ceto-darpana-marjanam).
Chaitanya Caritamrta Antya Lila 20.12 – Purport