Becoming a devotee of the Lord to serve material purposes is a great mistake. Many people become showbottle devotees for material profits. indeed materialistic persons sometimes take to professional devotional service and keep Visnu, the Supreme Personality of Godhead, as a means of livelihood. None of this, however, is approved. In the book known as Sapta-sati, as mentioned by Srila Bhaktisiddhanta Sarasvati Thakura, one can discover how a person worshiping the goddess Durga begs her for different varieties of material profit. Such activities are very popular among people in general, but they are the attempts of foolish, blind people (sei jnana-andha).

One should be completely free from all material desires and should serve Krsna simply to please Him. When people become interested in their own sense gratification (bhukti mukti siddhi kami), some of them desire to enjoy the material world to the fullest extent, some of them desire to be liberated and merge into the existence of Brahman, and others want to perform magic through mystic power and thus become incarnations of God. These are all against the principles of devotional service. One must be free from all material desires. The desire of the impersonalist to merge into the existence of Brahman is also material because such an impersonalist wants to gratify his senses by merging into the existence of Krsna instead of serving His lotus feet. Even if such a person merges into the Brahman effulgence, he falls down again into material existence. As stated in Srimad-Bhagavatam (10.2.32):

Because Mayavadi philosophers have no information regarding the transcendental service of the Lord, even after attaining liberation from material activities and merging in the Brahman effulgence, they must come down again to this material world.