Incredibly so. The term agnosticism is usually used when discussing/describing one's personal lack of or belief in God. The use in this context I'd say was carefully chosen to convey a false image to the idiot reader Walker is NOT a Christian. Utterly devious in my opinion. The last time I espied something similar was in accounts of a Louisiana political race describing his opponent's wife a "thespian."
The way I heard it, he not only told the crowd that his opponent's wife was a publicly admitted thespian, but in addition that she had for decades indulged in this behavior in front of paying customers, some of whom were children!!
To the Left, Obama is God. They're getting much more open about that fact every day.