Kṛṣṇa is addressed by Arjuna, pavitram. In the Upaniṣad it is said, Īśopaniṣad, apāpa-viddham (ISO 8). God cannot be infected by sinful activities. That is God's . . . just like we are infected by sinful activities, God is not like that. There is Absolute. So He is always pure. So we have to make ourselves purified before we can approach the Supreme Personality of Godhead.
So these are sinful activities: illicit sex life and meat-eating, unnecessarily killing the animals. Why should you kill animals? If God has given you so many nice foodstuffs—varieties of fruit, varieties of grain, sufficient milk—why should you take to this obnoxious foodstuff? But it is ill luck, unfortunate. By ill association they'll learned all this nonsense. So therefore one has to give up these nonsense habits. That is called tapasya. Tapo divyam.
Why tapasya? Divyam: for spiritual realization. Why it is necessary? Tapo divyaṁ yena śuddhyet sattva. Your existence will be purified, because . . . just like in diseased condition we cannot relish very palatable foodstuff. A man, jaundice, suffering from jaundice, if you give him something just like candy, sugar candy, he'll taste it as bitter because he is suffering from jaundice. But sugar candy is not bitter. Similarly, in our diseased condition, this material body, actually you cannot taste real happiness. That is not possible. Therefore we have to cure the disease.