Denise - I don't know if Berlin wrote God Bless America. I know he wrote America, which is the title of a song more commonly referred to by its opening line, My Country 'tis of thee.
And yes, the cause is secularization, not only of the Pledge. Which some of us would like changed to the Constitution not to the Flag, but hey, that's a whole 'nuther argument.
The Gubmint originally had E Pluribus Unum as our national motto. It was changed to In God We Trust to keep the "godless commie pinkoes" out in the 50's, and should revert back to E Pluribus Unum as soon as possible. Get the phrase In God We Trust off the currency, out of our schools, etc. We were founded as a secular nation to free ourselves from religious bigotry, let's not forget that.