Any Moral Theologians in the Audience?

Today in RCIA, my "cloistered brothers" and I were talking about venial and mortal sin.  Well, let me tell you, their frame of reference is exponentially different than mine.  The CCC definition of venial sin is 1862 One commits venial sin when, in a less serious matter, he does not observe the standard prescribed by the moral law, or when he disobeys the moral law in a grave matter, but without full knowledge or without complete consent.

Whereas, mortal sin,1859 Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God's law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart¹³³ do not diminish, but rather increase, the voluntary character of a sin.

"My cloistered brothers" pointed out that someone who committed 2nd degree murder committed a venial sin.  Well of course, that can't be correct but how would you explain this to them?

Second degree manslaughter is the unlawful killing of another person without implied or expressed malice, which is ill will toward someone. A charge of second degree manslaughter also indicates that the defendant had no intention of taking the life of the victim and that he or she took reasonable and ordinary action to prevent the victim's death. 

The First Catechism

One of the candidates in RCIA inadvertently told a joke.  Well, not so inadvertently, but it will make you think.  We were discussing how the catechism came about.  Someone noticed that in the book of Sirach, in the Bible, the introduction states that the

                       book was used to teach moral teachings to catechumens and the faithful.

So should Sirach be considered the first catechism?

When you think of it, most people couldn't read so there was no written catechism.  People taught orally.  Hence, statues, stained glass windows, and paintings.

But the educated must have written for instructions for others.  St. Augustin wrote the Enchiriodon. 
Should that be considered the first catechism?

One of the first things Martin Luther did was write a catechism--but that was the sixteenth century!  Luther prompted the Council of Trent to write a Catholic catechism.  Still, sixteenth century.

Mmmm.

That's when the class' smart aleck suggested, "Mary."
 Mary?
Yes!
Why do you say, Mary?
Because she said, "Do as he tells you."   
                                          John 2:5