Job Policy to only hire virgins[in a church, yes this serious]?

I work at a church and they are adding policy in the employee handbook that no employee can engage in sex before marriage and that if they find out you are thats misrepresenting the church and you can be fired. [In other words the only way they really know is if you get pregnant] Can this possibly be legal?? And this is in the daycare area of the church we are not pastors etc and not treated as such, this is in Texas, Can they really fire people for that? If yes please give evidence, if no please give evidence....thanks in advance.