When Hiranyakasipu asked Prahlada Maharaja, Where is your Lord? Is He present in this pillar? Prahlada Maharaja fearlessly replied, Yes, my Lord is present everywhere. Therefore, to convince Hiranyakasipu that the statement of Prahlada Maharaja was unmistakably true, the Lord appeared from the pillar. The Lord appeared as half lion and half man so that Hiranyakasipu could not understand whether the great giant was a lion or a human being. To substantiate Prahladas statement, the Lord proved that His devotee, as declared in Bhagavad-gita, is never vanquished (kaunteya pratijanihi na me bhaktah pranasyati). Prahlada Maharajas demoniac father had repeatedly threatened to kill Prahlada, but Prahlada was confident that he could not be killed, since he was protected by the Supreme Lord. By appearing from the pillar, the Lord encouraged His devotee, saying in effect, Dont worry. I am present here. By manifesting His form as Nrsimhadeva, the Lord also preserved the truth of Lord Brahmas promise that Hiranyakasipu was not to be killed by any animal or any man. The Lord appeared in a form that could not be said to be fully a man or a lion.