Intent of the Bill of Rights

The delegates to the Constitutional Convention were highly suspicious of centralized power, having just thrown off the British ruler. Their objective was to draft a document that gave sufficient authority to Congress and the federal government, but also dispersed power to the various branches of government and kept a great deal of authority in the states. The framers wanted to give Congress only certain listed powers and leave the rest of the power the individual states. Religiously speaking, the states at the time of the convention were diverse: some states allowed a form of religious freedom, while others had state churches that were supported through compulsory taxation. These state churches were given a preferred position over other denominations or churches. In fact, nine of the thirteen colonies had some form of state church, which were all Christian. Most of the representatives didn't want the federal government to meddle in the religious affairs of their states. For this and other reasons, many representatives weren't willing to sign the Constitution without the assurance the Bill of Rights would be forthcoming. Note that the ten amendments that make up the Bill of Rights all place limitations on the power of the federal government, reserving any other powers for the states or people.

David Barton has a book discussing this: Original Intent: The Courts, the Constitution & Religion