When God, the Supreme Person, comes into this world it is, of course, to protect his devotees and annihilate demonic disbelievers, but it is also to restore spirituality and spread spiritual knowledge, for the good of all living beings..
Spiritual knowledge cuts the knot of the heart. Spirit and matter are linked by the knot of the false ego. The false ego is wanting to dominate matter, but it is also the fact of identifying with one's body of matter and ignoring being, in truth, a spiritual soul. Now, this self-identification with matter exists for all souls conditioned by matter and illusory energy, and this knot becomes more and more tight as spiritual entities conceive of an excessive attraction to carnal pleasures. Avatar Rsabhadeva explained to his sons that the material universe is a place of attraction between male and female principles. This attraction takes the form of a knot in the heart, which tightens under the influence of material attachment. For those who long for material possessions as well as social bonds, friendship and love, this attachment, this knot, becomes very powerful.
Only instructions reviving spiritual knowledge can cut this knot and reduce it to pieces. No material weapon is required, for only authentic spiritual instruction can overcome it.
When the Lord appears in this material world, He spreads spiritual knowledge, in order to cut the knot of identification with matter.
The Lord comes in person to the material universe to reveal his spiritual and absolute entertainments there, as typically manifested in Vrindavana, Mathura and Dvaraka. It seems for the sole purpose of attracting conditioned souls to Him, so that they may return to their original home, in the eternal world. But for lack of piety, those who observe these entertainments of the Lord do not find them very attractive. Only those beings who have completely abandoned the path of sin and its consequences have access to the service of sublime love offered to the Lord. The set of Vedic ritual prescriptions (from the Vedas, the original holy scriptures) is precisely intended to lead conditioned souls on the path of godliness, and by strictly adhering to the principles set out for each group of society, one can acquire the qualities veracity, mastery of mind and senses, tolerance, etc., and thus be raised to the level where it is possible to practice pure devotional service. By this spiritual vision alone, all material aspirations are fulfilled.
When the Lord was present on earth, those beings who were fulfilled in all their material desires by the mere fact of contemplating him in truth, were able to return with him, in his kingdom. But those who could not see him as he is, remained attached to their material desires and could not return to the kingdom of God, their original home. And when the Lord disappeared from sight of all, it was still in his original, eternal form that He did so. He left this world in his own body; He did not leave his body here as dishonest and ignorant conditioned souls generally believe. Krishna appeared for the sole purpose of relieving the world from the undue burden