Gauranga Mantra established by Shrila Bhaktisiddhanta Sarasvati Thakura Prabhupada in 1911 -- By Swami Gaurangapada
Later in 1911 another controversy surfaced, challenging that the Holy Name of Gauranga chanted by Gaudiya Vaishnavas was not an eternal name of Godhead, was not found in the original Vedas, and that Lord Gauranga was not an incarnation of Godhead, but rather, by His own admission, a devotee of God.
Although it is clearly established in the pages of Chaitanya-bhagavata and Chaitanya-charitamrita that Lord Gauranga Mahaprabhu is the Supreme Personality of Godhead Himself, there were some persons who did not believe that His position as an avatara was revealed in the original Vedas. Of course one actual proof of Shri Gauranga Mahaprabhu's divinity was the darsanas He provided to a number of exalted devotees during the maha-prakasha manifestations in the home of Shrivasa Thakura, to Lord Nityananda as a six-armed Vishnu form, as Shad-Bhuja to Sarvabhauma Bhattacarya, as Radha-Krishna to Shrila Ramananda Raya, and so on. These proofs along with many convincing verses supplied by Krishna dasa Kaviraja and Vrndavana dasa Thakura in their Chaitanya-charitamrita and Chaitanya-bhagavata, repectively, were sufficient for reasonable men. But the more stubborn worldly scholars and critics wanted proof from the original Vedas. The smartas objected to the worship of the Deity form of Lord Shri Gauranga Mahaprabhu and claimed that the Gauranga-mantra was not an eternal Vedic mantra.
His Divine Grace Shrila Bhaktisiddhanta Sarasvati Thakura Prabhupada cited proof from the Shruti, particularly from the Caitanyopanisad from the Atharva Veda:
sa hovaca: rahasyam te vadisyami, jahnavi-tire navadvipe golokakhye dhamni govindo dvibhujo gaurah sarvatma maha-puruso mahatma maha-yogi trigunatitah sattva-rupo bhaktim loke kasyatiti. Tad ete sloka bhavanti
Brahma said: "I shall tell thee a secret! On the bank of the Jahnavi, at Navadvipa, which is called Goloka Dhama, shall Govinda, in a two armed form, as Gauranga, the Great One, the Great Mystic, Who is transcendental to the three modes of material nature, and Whose form is eternal, reveal Bhakti to the world! There are a number of verses in that regard." .
Other evidence was cited from the Svetasvatara Upanisad, as well as the Smrti, Tantras, Puranas, and especially the Shrimad-Bhagavatam. Shrila Bhaktisiddhanta Sarasvati Prabhupada addressed a large assembly at Navadvipa's Bada Akhada Hall, where many erudite scholars had gathered, headed by Shri Madhusudana Gosvami Sarvabhauma. He forcefully and brilliantly proved the eternality and glory of the Name, Form, Attributes, etc. of Shri Gauranga Mahaprabhu.
Although Shrila Bhaktisiddhanta Sarasvati Thakura was unaware of it, his own eternal spiritual master Shrila Gaura Kisora dasa Babaji was there in one corner of the meeting, and when he heard Siddhanta Sarasvati's lecture he was extremely pleased with him. All of the Gaudiya Vaishnavas who heard the discourse were filled with bliss and began to chant Shrila Bhaktisiddhanta Sarasvati Thakura's glories again and again. Due, in large measure, to Shrila Sarasvati Thakura's strong preaching on this point throughout his life, the Deity form of Shri Gauranga Mahaprabhu is now worshipped and accepted all over India as the eternal form of the Lord, and many thousands have received the Gauranga mantras with great faith and for eternal benefit. (From the Ray of Vishnu Chp 7 by Rupa-vilasa dasa prabhu).