In this connection, Śukadeva Gosvāmī speaks in the Sixth Canto of Śrīmad-Bhāgavatam, 2nd Chapter, 17th verse, 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 of "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.
Another example is given in the Śrīmad-Bhāgavatam of the elephant who enters into a lake and takes a bath very seriously, cleansing his body thoroughly. Then as soon as he comes onto shore he again takes some dust from the earth and throws it over his body. Similarly, a person who is not trained in Kṛṣṇa consciousness cannot become completely free from the desire for sinful activities. Neither the yoga process, nor philosophical speculations, nor fruitive activities can save one from the seeds of sinful desires. Only by being engaged in devotional service can this be done.
There is another evidence in the Fourth Canto of Śrīmad-Bhāgavatam, 22nd Chapter, 37th verse, wherein Sanat-kumāra says, "My dear King, the false ego of a human being is so strong that it keeps him in material existence as if tied up by a strong rope. Only the devotees can cut off the knot of this strong rope very easily, by engaging themselves in Kṛṣṇa consciousness. Others, who are not in Kṛṣṇa consciousness but are trying to become great mystics or great ritual-performers, cannot advance like the devotees. Therefore, it is the duty of everyone to engage himself in the activities of Kṛṣṇa consciousness in order to be freed from the tight knot of false ego and engagement in material activities."
This tight knot of false ego is due to ignorance. As long as one is ignorant about his identification, he is sure to act wrongly and thereby become entangled in material contamination. This ignorance of factual knowledge can also be dissipated by Kṛṣṇa consciousness, as is confirmed in the Padma Purāṇa as follows: "Pure devotional service in Kṛṣṇa consciousness is the highest enlightenment, and when such enlightenment is there, it is just like a blazing forest fire, killing all the inauspicious snakes of desire." The example is being given in this connection that when there is a forest fire the extensive blazing automatically kills all the snakes in the forest. There are many, many snakes on the ground of the forest, and when a fire takes place, it burns the dried foliage, and the snakes are immediately attacked. Animals who have four legs can flee from the fire or can at least try to flee, but the snakes are immediately killed. Similarly, the blazing fire of Kṛṣṇa consciousness is so strong that the snakes of ignorance are immediately killed.