Hare Krsna,
“Apparently the serpent named Aghāsura, because of having received association with Kṛṣṇa, attained mukti by entering Kṛṣṇa’s body. Entering the body of Kṛṣṇa is called sāyujya-mukti, but later verses prove that Aghāsura, like Dantavakra and others, received sārūpya-mukti. This has been broadly described by Śrīla Viśvanātha CakravartīṬhākura with references from the Vaiṣṇava-toṣaṇī of Śrīla Jīva Gosvāmī. Aghāsura attained sārūpya-mukti, being promoted to the Vaikuṇṭha planets to live with the same four-armed bodily features as Viṣṇu.” (SB 10.12.33 Purport)
This is a unique case of a demon attaining sārūpya-mukti. Usually demons in Krsna lila attain sāyujya-mukti by merging into the effulgence of the Supreme Lord. Aghāsura’s liberation is unique because he first obtained sāyujya-mukti and then sārūpya-mukti.
The question is why Aghāsura’s attained sarupya-mukti even though he was a demon and tried to kill Krsna and His cowherd friends. There are various reasons according to the scriptures.
As we have seen with the pastime of Nalakuvera and Manigriva, a saint’s (like Narada Muni) curse could become a blessing and blessing a curse. Similarly it is mentioned in Garga Samhita 2.6.15: “By Aṣṭavakra’s curse Aghāsura became a snake, and by Aṣṭavakra’s blessing Aghāsura attained a liberation even the demigods cannot attain.” Here is an indication why Aghāsura attained sarupya-mukti.
Another reason: Sukhadev Goswami explains that Aghasura didn’t get impersonal liberation. He got personal liberation, to actually go to the spiritual world to have a loving relationship with the Lord. Why did he get that? And our Acharyas explain, because somehow or other those little gopas were so happy going in his mouth. And he appreciated their happiness for a moment, and because there was that slight little attachment to these cowherd boys, he was given this liberation in Vaikuntha, the spiritual world. To become attached to devotees, to become attached to giving pleasure by serving devotees is the path by which Krsna reveals Himself to us.
Aghasura’s purpose was to kill Krsna. Krsna liberated him for at least two reasons: Aghasura thought of Krsna with devotion for a moment, and Krsna and His associates enjoyed sporting within Aghasura’s mouth.
Srila Visvanatha Cakravarti Thakura writes in his commentary on verse 39: Krsna’s awarding liberation to His enemies is a remarkable quality in His completeness. Kåñëa reciprocates according to the mood of the person approaching Him. From the statement that Aghäsura’s body became the playground for the boys for many days, it should be understood that the demon’s unfavorable attitude had been transformed into a favorable attitude. Aghäsura had attained särüpya-mukti in Vaikuntha, but he did not attain a form in Våndävana because of his lack of vraja-bhakti.
Incidents like this show that Krsna sometimes grants salvation to someone who thinks of Him only once or even by force. How much more fortunate must be those who always lovingly think of the Lord within their hearts, and especially those who chant His Holy Name regularly, sincerely, and lovingly.
This is the special quality of Krsna. Kåñëa’s awarding liberation to His enemies is a remarkable quality in His completeness. Krsna reciprocates according to the mood of the person approaching Him.
All glories to Srila Prabhupada!
Krsna Katha 