Sin is basically a personal offense against God, a turning from God. For this reason it is important to distinguish between actions that are done with knowledge and freedom and those which are not. Some actions that are in themselves wrong are done without personal guilt because the doer acts in ignorance or without freedom. The actions in these cases are to be distinguished from sin in the strict sense, sometimes called formal sin, in which one freely and knowingly does what he judges to be wrong. A formal sin is a deliberate violation of the known will of God.
Sin is first of all the rejection of simple, ordinary human reason.
There is a way in which we are supposed to act. There is a direction to life that we can recognize. Deep within us is the voice of conscience that calls us to act in a way which corresponds to that natural moral law which is God s creation.