Please see this beautiful biblical teaching on sin, and its forgiveness through Christ, which is our Light and our Life. St. Cyril was Bishop of Jerusalem in the mid 4th century and people still avidly read his writings sixteen and a half centuries later. This particular Lecture is one of 23 given to those about to be baptized.

You can read all of his 23 Lectures at this site, you will be glad you did. Also, you can learn about the man himself at this site.