When God incarnates, He has two missions-to vanquish the demons and deliver the sadhus, the faithful devotees. The word sadhunam, which means “saintly persons,” refers to devotees. It has nothing to do with worldly honesty or dishonesty, morality or immorality; it has nothing to do with material activities. Sometimes we may think that the word sadhu refers to a person who is materially good or moral, but actually the word sadhu refers to one who is on the transcendental platform. A sadhu, therefore, is a devotee, because one who engages in devotional service is transcendental to material qualities (sa gunan samatityaitan).
When Kṛṣṇa appears, He protects the devotees and kills the demons. Therefore Kṛṣṇa in His Narayana form has four hands. In two hands He holds a disc and club with which to kill the demons, and in the other two hands He holds the conchshell and lotus with which to bless and protect the devotees. The Lord says, kaunteya pratijanihi na me bhaktah pranasyati. Thus Kṛṣṇa bugles with His conchshell, “My devotees will never be vanquished.” And with the lotus flower He extends His blessings. The lotus flower, which sometimes also appears in the hand of Laksmi, is a symbol of blessings. Now some may say that Kṛṣṇa appeared for this purpose or that purpose, but the real conclusion is that Kṛṣṇa appears for His own pleasure, not because He is bound by any other cause. We take our birth because we are bound by our karma, but Kṛṣṇa, being fully independent, does not come because of someone else’s request or because of karma. Rather, He comes by His own free will (atma-mayaya). We are compelled to take birth because of Kṛṣṇa’s external, material energy, but Kṛṣṇa is not controlled by the maya, or energy, of anyone else, and therefore He does not take birth in such a condition. Maya, the illusory energy, is under the control of Kṛṣṇa, so how could maya control Him? One who thinks that Kṛṣṇa, like us, is controlled by maya is described in Bhagavad-gita as mudha, a fool (avajananti marh mudha manusim tanum asritam).
Source : A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Teachings of Queen Kunti”, Page 85, 134