That's the same thing Catholics say about Protestants. The Protestant retort is that he is led by the Holy Spirit.
They differ over the interpretation of scripture and tradition (history), but each recognizes the apostolic origins and authority of both.
When I asked if there was a "book" for the new thought folks, the answer was something about using different materials as each individual feels like it.
There is no authority to which one can appeal to validate teachings. It sounds like they make it up as they go.