Sometimes people think that once a person has performed sinful acts, especially acts that are grievously sinful, he must be regarded as a sinner forever. This notion runs contrary to Vaishnava philosophy.
The Brihad-vishnu Purana says:
namno hi yavati saktih
tavat kartum na saknoti
patakam pataki narah
“Simply by chanting one holy name of Hari, a sinful man can counteract the reactions to more sins than he is able to commit.”