With freedom comes responsibility. We are responsible for our moral behaviour because we are made in God's image as rational beings, capable of knowing what the morally right and good thing to do is and as free beings, capable of choosing to do the morally right and good thing. These two capacities, to know and to choose, together form what is called conscience. Loosely translated, conscience means 'with knowledge'. In other words, when we make moral choices, we make them based on what we know about the goals we want to achieve, the ways or means to achieve them, the circumstances in which we need to achieve them and the consequences of both the means we choose and the outcomes we achieve. When we have weighed all these things, we make a judgment based on our knowledge of what the morally right thing to do is. We are then obliged to follow our conscience and do the morally right thing, taking responsibility for our decision.

We must be careful about balancing two things: first, the reality of the influence of evil and sin from sources beyond our control, and second, taking personal responsibility for what is within our control. Neil Ormerod (2007) offers a contemporary interpretation of original sin in terms of the experience of victimhood. In doing so, he highlights the question of responsibility and those factors that lessen or, even remove responsibility in certain human situations. The human reality is that we are influenced by genetic, social and cultural factors that are, to a lesser or greater extent beyond our control. In the light of such factors Ormerod makes the point, regarding original sin, that we are 'first and foremost sinned against'. From the time of our birth and into early childhood, this being 'first and foremost sinned against' entails a 'human brokenness, an interior shattering or distortion of consciousness that muddies our search for direction in the movement of life' that brings with it a 'weakened sense of our own worth which inclines us, with a statistical inevitability, to sin' (p. 79; citing Moore 1985, xiii).

Since conscience is your own relationship to the objective moral truth, you are obliged to follow your conscience. In other words, what one determines to be good and right based on the use of one's reason is like a law that must be obeyed (Gaudium et spes, 16). It is the closest approximation one has to the truly good. It is the way that one participates in God's goodness. It is here that one is 'alone with God, whose voice echoes' in one's depths (GS 16). So, to not obey your conscience, to choose not to do what you know to be the morally right thing to do or to blindly obey others is to abdicate personal responsibility for moral decisions. to act in this way is a sin because it is tantamount to idolatry. If conscience is where we relate most closely at a personal level with the objective truth of God and perfect goodness, then to do other than what we believe to be right and true in our conscience is to do other that what we believe to be God's will, to do other than what we believe to be perfect goodness. That is the essence of what we mean when we talk about sin.