"In God" wasn't added until (I think) 1957. Until then it was One Nation Indivisible.
I too see the In God addition as an attempt to Christianize a nation that is, in fact, not solely Christian and has people who, like yourself, don't believe in ANY 'higher power'.
I wish they would drop it and go back to the original. I love saying the Pledge of Allegiance, but am also sad every time I do because I feel like it's just one more place I have to 'push against' for equal treatment/acknowledgement.
Deborah