When did Christianity shift into its current political form?

This is my first thread, so I'm sorry if it is jumbled and unorganized. It just popped into my head recently and I'd like to hear other's thoughts on it.

As Americans, we live by certain base principles and laws, and we are given certain basic rights as humans and American citizens. If you choose to become a Chirstian, you are agreeing to follow additional rules and laws. Chirstianity has its own defined set of principles and laws in addition to the laws and principles of America. Living the life of a good Christian is supposed to be a sacrifice and a personal rejection of the "overly lax" laws we currently have. That's all fine and dandy.

Many Chistians look at secular America and say "Hey! that's not fair! They get to do such and such but I can't!" This is also part of the sacrifice of living a Christian life. This issue that is arising now and is very concerning to me, is that we have Christians in positions of political power who think "If I can't do this or that, nobody can." They are unwilling to live with their additional laws and principles, yet seek to make everyone follow these more stringent guidelines, because they still have to make it so God is never wrong or not the supreme being...When did they get so concerned with the way everyone else lives? Why does it even matter to them? Does it affect their own personal salvation for some inexplicable reason? Why do they even concern themselves with anybody else's personal journey? Why must they feel they need to push their personal beleifs onto the entire counrty? Why must they force everyone else to play by their additional rules?

I know I have not articulated this in the way my mind sees it, but hopefully my point has come across nonetheless. Thanks for your time everyone!