Well, one should contemplate for a moment the "integrity" and "coherence" that laws should encourage with a person and within society. 

God made us to be serene, with a reconciled intellect, will, and set of emotions or passions.  They are not naturally reconciled.  We don't have perfect dominion over our faculties.  Takes effort, virtue, beginning again, help from God. 

When there is a fissure or discordance among these human faculties, there is unpeace with in us. We should not believe one thing..and say another.  We shouldn't believe something is sin and yet allow our selves to do it without consequence. 

If laws make something illegal..and there is no proportionate consequence to behavior as a result...there is introduced a gaping fissure and inconstancy in society, that works its way into a person.