Actually the Lord’s name already exists because of His transcendental activities. The Lord is sometimes called guna-karma-nama because He is named according to His transcendental activities. For example, Krsna means “all-attractive.” This is the Lord’s name because His transcendental qualities make Him very attractive. As a small boy He lifted Govardhana Hill, and in His childhood He killed many demons. Such activities are very attractive, and therefore He is sometimes called Giridhari, Madhusudana, Agha-nisudana and so on. Because He acted as the son of Nanda Maharaja, He is called Nanda-tanuja. These names already exist, but since nondevotees cannot understand the names of the Lord, He is sometimes called anama, or nameless. This means that He has no material names. All His activities are spiritual, and therefore He has spiritual names.

Generally, less intelligent men are under the impression that the Lord has no form. Therefore He appears in His original form as Krsna, sac-cid-ananda-vigraha [Bs. 5.1], to carry out His mission of participating in the Battle of Kuruksetra and pastimes to protect the devotees and vanquish the demons (paritranaya sadhunam vinasaya ca duskrtam [Bg. 4.8]). This is His mercy. For those who think that He has no form and no work to do, Krsna comes to show that indeed He works. He works so gloriously that no one else can perform such uncommon acts. Although He appeared as a human being, He married 16,108 wives, which is impossible for a human being to do. The Lord performs such activities to show people how great He is, how affectionate He is and how merciful He is. Although His original name is Krsna (krsnas tu bhagavan svayam [SB 1.3.28]), He acts in unlimited ways, and therefore according to His work He has many, many thousands of names.

From Srila Prabhupada’s purport to SB 6.4.33