This was the very first episode of CSI that I have ever watched.  The only reason I watched it was because it involved the Catholic Church, and a priest suspected of murder.  The victim was found strangled by a rosary, and was crucified, hanging from the rafters of a church.  (How could I not watch this show!) 

This episode had a number of themes worth mentioning.

• God or the girl?  The priest was willing to leave the priesthood for the love of a woman.  Deciding whether to pursue the priesthood or to pursue married life is something that almost every young man considering the priesthood wrestles with.
• Confession.  The priest cannot reveal any sins revealed in the confessional.  The true murderer confessed to killing the victim "for cheating on me with you", for cheating on him with the priest, that is.  That angered the priest so much that he jumped out of his stall and assaulted the guilty man.  Yet later when questioned, the priest did not reveal who the true murderer was, but instead, sacrificed his own innocence by falsely saying that he himself was the murderer - thus protecting the guilty.  The innocent sacrificing his own life for the guilty... sounds like something Christ himself did by dying on the cross for us all.
• Guilt.  The episode played on this a lot.  For example, the interrogator said to the priest, " In our world you're either innocent or guilty."  The priest replied, "In my world you can be both."  So, how so?  I can feel guilt for knowing that someone was murdered, even though I am innocent in that person's death.  There are countless other examples.
• Forgiveness.  At the end of the episode, the priest is asked by an authority, regarding the murderer, "Can you forgive him?"  The priest replies, "That's Christ's mandate.  You know what that means."  The authority responds, " You have no choice."  The way Catholics express love for God is by loving their neighbour, which involves forgiveness... forgiveness of friend and foe.  No, it's not easy - if it were, are world would be a lot more peaceful, but people hold grudges, anger, hate, and thus we end up with all the quarrelling and fear that is in our world today.