One who really wants to know Kṛṣṇa must follow the path He prescribes in the Bhagavad-gītā (18:55): bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ. "One can understand Me as I am, as the Supreme Personality of Godhead, only by devotional service." Except for devotional service, there is no way to understand Kṛṣṇa. When Lord Kṛṣṇa appeared in the form of Lord Caitanya Mahāprabhu, He gave the same instruction about attaining Kṛṣṇa through devotional service, so it is certain that Kṛṣṇa can be approached only in this manner. Following in the disciplic line of Lord Caitanya, the six Gosvāmīs of Vṛndāvana have written extensive literature with detailed explanations of Lord Kṛṣṇa. These confidential revelations are yet to be properly broadcast in the world. The Gosvāmīs' esoteric logic and profound analytical philosophy have not yet caught the attention of modern thinkers, and the burden of guilt for this discrepancy must indeed fall on us. The Gauḍīya Maṭha mission was founded to propagate the words of Śrīla Rūpa Gosvāmī and Śrīla Raghunātha dāsa Gosvāmī.
The gigantic universal form that Lord Kṛṣṇa exhibited to Arjuna is certainly not the quintessence of the Lord's divine mood. In fact, the two-handed human form of Kṛṣṇa playing the flute is the superexcellent manifestation of the Lord. But one must not make the mistake of thinking that because Lord Kṛṣṇa appears as a human, He is human. His form is eternal and full of knowledge and bliss, unlike an ordinary mortal's. He is not even an extraordinary human being. The human form may be a facsimile of the Supreme Lord's transcendental form, but that does not make God a man, or vice versa. The Bible and other scriptures state that man was made according to the form of God, but that does not imply that God is a man.
There is substantial proof in the Gītā that those who thoroughly grasp the truth about God will, upon leaving the material body, enter the spiritual realm and be with God. Only those who realize God as the eternal Supreme Personality can become immortal. This realization is the human being's prerogative alone, and one who attains it reaches the highest perfection. Once achieving perfection, the jīva never returns to this temporary world of birth, death, old age, and disease. Only those who discipline their lives so as to attain this objective fulfill the purpose of their human birth; others plunge into oblivion.