I believe that forgiveness and faith go hand-in-hand.  To accept the Lord into your life as your Saviour, you must have faith in His existance and His ability to save.  You also ask for forgiveness for transgressions - with the belief (faith) that they will actually be forgiven.  You can't ask for forgiveness, either, without the belief that Jesus can forgive sins. 

As you continue to use prayer in your life, you do so with the continued believe/faith that there is a God in heaven who created the world and cares for you.  You also continue to ask forgiveness of sins.  Again, these things go hand-in-hand.  As without faith - why even ask for forgiveness?  Why even pray?