1 Timothy 1 12 I thank him who has given me strength, Christ Jesus our Lord, because he judged me faithful, appointing me to his service, 13 though formerly I was a blasphemer, persecutor, and insolent opponent. But I received mercy because I had acted ignorantly in unbelief, 14 and the grace of our Lord overflowed for me with the faith and love that are in Christ Jesus. 15 The saying is trustworthy and deserving of full acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost. 16 But I received mercy for this reason, that in me, as the foremost, Jesus Christ might display his perfect patience as an example to those who were to believe in him for eternal life. 17 To the King of ages, immortal, invisible, the only God, be honor and glory forever and ever. Amen.
I also really like Acts 26, I believe that between these scriptures we can clearly see that even if you feel that you are the worst of the worst, the lowest of the low it doesn't matter because through God's limitless love and boundless grace you will still be forgiven and cleansed, made new :)