In our life, we knowingly or unknowingly, sometimes commit the sin. In scriptures there are many ways such as penance, charity etc. are told, through which atonement to such sins can be attained. But there is no way more swift, fast for atonement to sins than Devotional service to Lord Krishna. In this regard Bhagwat Puran & Bhagwat Gita, both explain about this assurance in detail that Devotion to Lord Krishna is the supreme purifier for all the sins that a person commits in life time. Below are few verses from Bhagwat Puran regarding this:
"Some manage, in relying on nothing but an unalloyed devotion towards Lord Krishna, to destroy all their badness beyond revival, like the sun does with fog."
"A man full of sin, o King is for certain not as much purified by penance, as the devotee who has surrendered his life to Lord Krishna in dedicated service unto the original person of God."
"In this world there is this path that is really appropriate & the one that is followed by the well-behaved, fearless and auspicious, saintly people; that is in surrendering oneself to Lord Krishna.
"Most of the atonement, well performed by a nondevotee will not purify, o King, like all the rivers can't purify a liquor jar with their regular washing of it."
"Once the mind is of full of surrender to the two lotus feet of Lord Krishna & the mind is full of hankering after Lord's qualities, then that person shall never encounter Yamarâja (Lord of death) and his superintendents, or even in one's dreams meet his servants carrying the ropes to bind, because doing such devotional service to Lord Krishna is the right atonement for all sins."
In Bhagwat Gita also God himself is giving that assurance:
mam ekam saranam vraja
aham tvam sarva-papebhyo
mokshayisyami ma suchah" (Bhagwat Gita: Chapter Eighteen verse 66)
"Sri Krishna said: O Arjuna, Abandon all varieties of religion and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear."
"karma-jam buddhi-yukta hi
phalam tyaktva manisinah
padam gacchanty anamayam" (Bhagwat Gita: Chapter Two verse 51)
"Sri Krishna said: By thus engaging in Devotional service to the God, great sages or devotees free themselves from the results of work in the material world. In this way they become free from the cycle of birth and death and attain the state beyond all miseries."
So let's always pray to Lord Krishna & let's always engage our mind in devotional service of Him. Let's read religious texts, scriptures & literature regarding the Lord Krishna. Let's always sing His glories so that He can always be merciful on us. If we shall do such devotional service to God then we shall get special mercy of Lord Krishna & we shall be purified of all the sins in our life.
Jai Sri Krishna.