Being an ordained minister, I'm really curious on why and how you equate any Christian faith with freedom... doesn't it say "Thy [God's] will be done"?
Human freedom, as a foundation upon which the Christian world-view is built, comes out of the image and likness with which God created us (Gen 1:26). Thus, we are in His image and are capable of being like Him. God is ultimately free — He freely created the world, He freely gave us His image and likeness, He freely gave us His Covenants and freely gave us His Only-Begotten Son who freely went to the Cross. There is nothing that compelled Him against His will to do any of these things. As such, we must be free because we are in His image and likeness. This is why He allows us the freedom to accept or reject Him. Any kind of coercion on His part, whether by arbitrarily destroying evil in the world or through any kind of predestination, would destroy His image and likeness in His creation. Without freedom, we cease to be human — we cease to be the image and likeness of God.
When we say "Thy will be done" we are freely choosing to make the Lord's Prayer our own and to orient our lives toward God. We are freely choosing to be the unique and unrepeatable person we are supposed to be — a friend of God. We freely choose the ultimate, unending, inexhaustible and ineffable wisdom and love of God over and above the fallen world.
In terms of RPGs, I choose to allow Christ into my gaming and try to game in a way that expresses my faith in Him. I find doing so much easier when the system I play allows for the freedom to play the game in any number of ways. There is no single true way to play our hobby, nor is there ever going to be the perfect system. One of the main reasons for this is because of us. As human beings we all bring something unique to the table. As such, every gaming table is unique. This is not something that is detrimental, it is something to be celebrated.
As a result, I find any mechanic that removes this humanity — this uniqueness — takes something away from my game. This is why I choose to play the way I do — using systems that not only allow, but encourage players to go their own unique way.