Many governments have used Christianity to govern people as it has a strong emphasis on Moral behavior, which is something the SCOTUS and POTUS are now doing away with. I did not read the ad, did it imply that the "Founding Fathers" were all Christians ? Or did it imply they used Christian Principles to craft the Constitution ? I believe you might even find this helpful and scholarly and it might even help to dispel the stereotypes you commonly use : https://www.gracechurch.org/sermons/7112