It's something he said on the campaign trail back in 1987 when he was Vice-President and made a stop off in Chicago (August 27th 1987).
God Bless The Land of the Free....and all that....
Robert Sherman: "What will you do to win the votes of Americans who are atheists?"
George HW Bush: "I guess I'm pretty weak in the atheist community. Faith in God is important to me."
Robert Sherman: "Surely you recognize the equal citizenship and patriotism of Americans who are atheists?"
George HW Bush: "No, I don't know that atheists should be considered as citizens, nor should they be considered patriots. This is one nation under God."