This is simply untrue. Theologically conservative Christians–even theologically conservative Christians who are by various measures politically conservative (and not all theologically conservative Christians would be considered politically conservative in U.S. terms)–do not agree at all on a whole lot of issues. Some theologically conservative Christians are very strong supporters of strict church-state separation. Their reasoning may be completely different from mine–they may believe that the state is a corrupt or even essentially Satanic institution, part of fallen and sinful world, from which the church must be protected by keeping the state completely out of religion, or perhaps that the state is a necessary institution, given the fallen state of humanity, but one to which God has given no power over matters of religion–but to the extent our totally different reasoning processes come to the same conclusions, I would count them as political allies.
Frankly, I think your claim here would be considered prejudiced or even bigoted if it were made by an atheist.
“Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof…”
The United States is NOT just a country where “the majority rules”. The Constitution removes some things from the authority of the state, even when the state governs according to the will of the majority. How to or whether or not to worship the “creator”–in other words, what the first four of the Ten Commandments are all about–are things over which the state has no authority in this country.