Probably not. But I think Arnold has made the word "republican" less repulsive to a lot of more middle of the road democrats. In the recall election republicans won over 60% of the statewide vote. A turnout like that again could spell a victory for Bush.
There are a number of things that Arnold could do in California that would open the way for a Bush advance in the state. The last poll I saw had the pres. behind now by only 8 points. That's in the range of making this a targetable state.
The Christian vote in California has to turn out. I think Arnold could work on that angle in a variety of ways.
I can't imagine a real, biblically based Christian voting in any other way.