न हि ज्ञानेन सदृशं पवित्रमिह विद्यते |
तत्स्वयं योगसंसिद्ध: कालेनात्मनि विन्दति || 38||

na hi gnyaanena sadrusam pabitramiha vidyate
tat swayam yog samsiddhah kaalenaatmani bindati
(Bhagavad Gita Chapter4 Verse38)

To be free from evils and sufferings, one has to have knowledge. This is purity, freedom from sins. Real knowledge is experience. The experience comes from actions, which are physical, mental, verbal, and vital. Right knowledge comes from the right action. Right knowledge is purifying.