Wow, you really need a history lesson (not to mention a lesson in the difference between plural and possessive in written English) before you write on this topic.

If you believe that Christianity came into prominence because it stood against "earthly power," you are ignorant of the topic you're trying to address.

In its earliest days, Christianity reached toward power, becoming the mandatory state religion of the Roman empire by the 4th century CE and then partnering with Rome to brutally suppress other faith systems.

You should learn about that history.

P.S. "Christians" means more than one Christian. "Christian's X" refers to the fact that X is possessed by a Christian.