It is impossible for anyone in the Christian world to lack a concept of sin. Everyone in Christianity from early childhood on is taught what evil is, and from youth on is taught which evils are sinful. . . . The evil that is sinful is simply evil against our neighbor; and evil against our neighbor is also evil against God, which is what sin is.
Nevertheless, having a concept of sin does nothing for us unless we examine the actions we have taken in our lives and see whether we have either openly or secretly done any such thing.
Before we take this action, everything about sin is just an idea to us; what the preacher says about it is only a sound that comes in our left ear, goes out our right ear, and is gone. Eventually it becomes a subject relegated to vague thoughts and mumbled words in worship, and for many it comes to seem like something imaginary and mythical.
Something completely different occurs, however, if we examine ourselves in the light of our concepts of what is sinful, discover some such thing in ourselves, say to ourselves, “This evil is sinful,” and then abstain from it out of fear of eternal punishment. Then for the first time we receive the instructive and eloquent preaching in church in both of our ears, take it to heart, and turn from a non-Christian into a Christian.
What could possibly be better known across the entire Christian world than the idea that we should examine ourselves? Everywhere in both Roman Catholic and Protestant empires and monarchies, as people approach the Holy Supper they are given teachings and warnings that they must examine themselves, recognize and admit to their sins, and start a new life of a different nature. In British territories this is done with terrifying threats. During the prayer that precedes communion, the priest by the altar reads and proclaims the following:
The way and means of becoming a worthy partaker in the Holy Supper is first to examine your life and your conversations by the rule of God’s commandments. In whatever regard you notice that you have committed an offense of will, speech, or act, then bewail your own sinfulness and confess yourselves to Almighty God, with full purpose of amending your life. If you observe that your offenses are not only against God but also against your neighbors, you shall reconcile yourselves to them, being ready to make restitution and satisfaction to the utmost of your power for all injuries and wrongs done by you to any other, and being likewise ready to forgive others who have offended you, just as you wish to have forgiveness from God for your offenses. Otherwise receiving the Holy Supper does nothing but increase your damnation. Therefore if any of you is a blasphemer of God, or a hinderer or slanderer of his Word, or an adulterer, or someone taken with malice or ill will, or involved in any other grievous crime, repent of your sins. Or else do not come to the Holy Supper; otherwise, after you take it the Devil may enter into you as he entered into Judas, fill you with all wickedness, and bring you to destruction of both body and soul.
Nevertheless, there are some people who are incapable of examining themselves: for example, children and young men and women before they reach the age at which they can reflect upon themselves; simple people who lack the ability to reflect; all who have no fear of God; some who have a mental or physical illness; and also people who, entrenched in the teaching that justification comes solely through the faith that assigns us Christ’s merit, have convinced themselves that if they practiced self-examination and repentance something of their own selves might intrude that would ruin their faith and divert or redirect their salvation from its sole focus.
For the types of people just listed, an oral confession is of benefit, although it is not the same as practicing repentance.
People who know what sin is and especially those who know a lot about it from the Word and who teach about it, but who do not examine themselves and therefore see no sin within themselves, can be compared to people who scrape and save money, only to put it away in boxes and containers and make no other use of it than looking at it and counting it. They are like people who collect pieces of gold and silver jewelry and keep them in a safe in a storage room for no other purpose than to own them. . . .
from Regeneration, Pages 28-31