In the Bhagavad-gita it is clearly said by the Lord that the only way of not coming back to the material world is to be promoted to the spiritual planets. For the impersonalists there is no such assurance of not falling down in the whole Vedic literature. The conclusion is that without developing the spiritual body and without being situated on one of the spiritual planets, the so-called liberation is also illusion, or it is not complete. A spirit soul who falls down from the Brahmajyoti to the Kingdom of Maya may have a chance of associating with a pure devotee, and then he may be elevated to the spiritual planets of Vaikuntha or to Goloka Vrindaban. From the Brahmajyoti there is no direct promotion to the spiritual planets, and it is clearly stated in the Bhagavatam that such souls fall down: patanty adha.
Letter to Rupanuga, 24 July, 1969