Sin
Catholic Doors Ministry
Frequently Asked Questions about Sins: Mortal and Venial.
www.catholicdoors.com/faq/qu06.htm
Catholic Update
Understanding Sin Today
www.americancatholic.org/Newsletters/CU/ac0197.asp
Mortal Sin
The concept of mortal sin has been an integral part of the Christian message since the very beginning.
www.catholic.com/library/Mortal_Sin.asp
Sin
The Catechism of the Catholic Church's explanation of sin
www.vatican.va/archive/catechism/p3s1c1a8.htm
Sin
Sin according to the Catholic Encyclopedia
www.newadvent.org/cathen/14004b.htm