In this connection, Śukadeva Gosvāmī speaks in the Sixth Canto of Śrīmad-Bhāgavatam, Second Chapter, verse 17, about the story of Ajāmila, who began life as a fine and dutiful brāhmaṇa, but in his young manhood became wholly corrupted by a prostitute. At the end of his wicked life, just by calling the name "Nārāyaṇa (Kṛṣṇa)," he was saved despite so much sin. Śukadeva points out that austerity, charity and the performance of ritualistic ceremonies for counteracting sinful activities are recommended processes, but that by performing them one cannot remove the sinful desire-seed from the heart, as was the case with Ajāmila in his youth. This sinful desire-seed can be removed only by achieving Kṛṣṇa consciousness. And this can be accomplished very easily by chanting the mahā-mantra, or Hare Kṛṣṇa mantra, as recommended by Śrī Caitanya Mahāprabhu. In other words, unless one adopts the path of devotional service, he cannot be one-hundred-percent clean from all the reactions of sinful activities.
By performing Vedic ritualistic activities, by giving money in charity and by undergoing austerity, one can temporarily become free from the reactions of sinful activities, but at the next moment he must again become engaged in sinful activities. For example, a person suffering from venereal disease on account of excessive indulgence in sex life has to undergo some severe pain in medical treatment, and he is then cured for the time being. But because he has not been able to remove the sex desire from his heart, he must again indulge in the same thing and become a victim of the same disease. So medical treatment may give temporary relief from the distress of such venereal disease, but unless one is trained to understand that sex life is abominable, it is impossible to be saved from such repeated distress. Similarly, the ritualistic performances, charity and austerity which are recommended in the Vedas may temporarily stop one from acting in sinful ways, but as long as the heart is not clear, one will have to repeat sinful activities again and again.