Can't the fact that we believe in a loving God of justice and mercy be enough to distinguish us from the god of the Islamists which feeds off the violence perpetrated by its adherents?
As I stated on another thread here, the recognition that this is a nation "under God" is less the establishment of religion, and more an historical fact. Our nation was formed by the foundation that "all men are CREATED equal" and that they are "endowed by their CREATOR with certain inalienable rights" -- rights not created or granted by the whim of the state, but rights bestowed upon man by God. This is a critically important distinction. Eliminate this concept of God-given rights from the basis of our society and values, and what we have to revert to are rights and liberties that are derived from the power of the state -- and the state will always have the power to take those rights away.
The founders clearly acknowledged that this was a nation founded "under God" or Providence. The atheists may not like it, but this is historical fact, and as Americans who love their country, they should be willing to acknowledge that historical fact.