Srimad Bhagavatham 6:2: 16, 17
गुरूणां च लघूनां च गुरूणि च लघूनि च
प्रायश्चित्तानि पापानां ज्ञात्वोक्तानि महर्षिभिः
तैस् तान्य् अघानि पूयन्ते तपो-दान-व्रतादिभिः
नाधर्मजं तद्-धृदयं तद् अपीशाङ्घ्रि-सेवया
The maharishis who knew the comparative value of penances have laid down hard penances for the atonement of grievous sins and light penances for comparatively lighter ones.
Therefore, its is true beyond doubt that sins of all kinds are eradicated through atonement in the form of penances, charity, fasting and other forms of religious observances.
But when through repeated acts of sin the impulses or Samskaras of sin get deep rooted in the heart, they are not destroyed by ordinary acts of atonement. Even such impulses are totally uprooted by the Chanting of the Divine Names of God.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji