Devotion to God is the supreme purifier of all the sins that a person commits in his life time.
In Bhagavad Gita God himself is giving that assurance
Bhagavad Gita Chapter 9
TEXT 30
api cet su-duracaro
bhajate mam ananya-bhak
sadhur eva sa mantavyah
samyag vyavasito hi sah
bhajate mam ananya-bhak
sadhur eva sa mantavyah
samyag vyavasito hi sah
SYNONYMS
api--in spite of; cet--although; su-duracarah--one committing the most abominable actions; bhajate--engaged in devotional service; mam--unto Me; ananya-bhak--without deviation; sadhuh--saint; eva--certainly;sah--he; mantavyah--to be considered; samyak--completely;vyavasitah--situated; hi--certainly; sah--he.
TRANSLATION
Even if one commits the most abominable actions, if he is engaged in devotional service, he is to be considered saintly because he is properly situated.
Through the above verse, Krishna is telling Arjuna that even if the most sinful of person worships Him with full devotion, then He considers him to be a saint as he has rightly resolved in his life.
Let's all be devotees of the supreme personality of godhead, Lord Krishna.