kinda they are. Religion has been in the founding of our country, many of our founders were religious. Even our nations motto "In God we trust" has been reaffirmed over the years, with bipartisan support. It's on our money, and its posted in both yhe senate and house chambers. It's even encouraged to be posted in government buildings, schools, etc.
Yes, we have no laws establishing a religion, but religion has been around in our country from the beginning. That religion has been predominately Christianity.