Srila Prabodhananda Sarasvati has sung: kaivalyam narakayate. The impersonalist's conception of becoming one with the effulgence of the Lord is exactly like hell. Therefore, of the five types of liberation, the first four (salokya, samipya, sarupya and sarsti) are not so undesirable because they can be avenues of service to the Lord. Nonetheless, a pure devotee of Lord Krsna rejects even these types of liberation; he aspires only to serve Krsna birth after birth. He is not very interested in stopping the repetition of birth, for he simply desires to serve the Lord, even in hellish circumstances. Consequently the pure devotee hates and fears sayujya-mukti, merging into the effulgence of the Lord. This merging is due to an offense committed against the transcendental loving service of the Lord, and therefore it is not at all desirable for a pure devotee.