President Bush's messianic attitude stems from his belief he was "chosen" by God to be the President of the United States.

“The president’s fault is not that he has been too messianic: It is rather that he has not been messianic enough.”
"The president’s detractors ridicule as “Bush babble” the rhetoric of his Second Inaugural Address, the high-water mark of his Freevangelical policy; and, as distressing news pours forth from Iraq, they point to his claim that “eventually the call of freedom comes to every mind and every soul” as evidence that he suffers acutely from a Messiah complex. The criticism misses the mark"
— MICHAEL KNOX BERAN