I don't think this is quite true, because before applying the principle of Occam's razor, all other differences between the competing theories have already been removed. It is an "other things being equal..." principle. In the example of Newton versus Einstein, the two theories do not equally accurately describe/predict the available observations with the same accuracy.
I'm not sure if you are agreeing with my definition or not? If not then I get your point that Occam's razor is supposed to be applied to two competing theories which are considered to be equal. It was meant as a scientific tool and it is probably misused quite a bit in general language.
But if you use Newton to predict the movement of a body on the surface of the earth falling in a vacuum and you use Einstein's theory then you'll get the same answer to a certain decimal place. So at this level, the level where Newton works, the two theories could be said to make the same predictions. At which point you can say Newton is simpler and therefore more likely to be right according to occam's razor. This is why I say occam's razor is not 'the simplest theory is more likely to be correct' but instead it is the 'theory with the least assumptions is more likely to be right'. Certainly this is the dictionary definition if not the commonly used definition. Also if you could argue that occam's razor was commonly used in terms of simplest then I would say this was a misuse and not helpful.
So God theory is the ultimate Occam's razor: it uses one assumption, "God's will" and it applies to everything.
As soon as you say 'God's will' then you create many assumptions. Who is God, what is God, what is his will, why is his will, where is God, when is God, who made God, why did they do that, what properties does God have? etc etc etc.
Technically as Steve points out two theories have to be somewhat equal to start with before it even makes sense to think about Occam's razor. A theory makes a falsifiable prediction starting with a hypothesis and then uses evidence to prove or disprove the theory. Saying God made it that way is not a competing theory, as no falsifiable predictions are made and no evidence can be found to prove or disprove. So the vast majority of the time Occam's razor is superfluous as it isn't the case that there are two competing theories.
Where you can use Occam's razor is in cases where the two theories are the same but theory A states God made it this way and theory B simply doesn't posit a cause. In these cases Occam's razor will remove the assumption of God as being likely.
Please note Occam's razor is in no way a proof, and is in no way meant to be a proof. It is meant to be a tool and like all tools can be misused.
Unknown means unknown.