Our great country was founded upon the principle of freedom, and with freedom comes freedom of religion, and freedom from religion. The founding fathers intended the United States to be a secular nation, and to be religiously neutral.
The addition of "In God We Trust" on our currency, a change made in the 1950's, I believe violates said principle, and I believe that in order to become a more free and secular nation, we should have religious imprints on our currency removed.