From the Wikipedia article on the song:
Music critic Jody Rosen comments that a 1906 Jewish dialect novelty song, "When Mose with His Nose Leads the Band," contains a six-note fragment that is "instantly recognizable as the opening strains of 'God Bless America.'". He interprets this as an example of [Irving] Berlin's "habit of interpolating bits of half-remembered songs into his own numbers....The original lyric was "Stand beside her and guide her to the right with the light from above."
In 1938, with the rise of Hitler, Berlin, who was Jewish and a first-generation European immigrant, felt it was time to revive it as a "peace song," and it was introduced on an Armistice Day broadcast in 1938, sung by Kate Smith on her radio show. Berlin had made some minor changes...
... by this time, "to the right" might have been considered a call to the political right, so he substituted "through the night" instead.