Christianity has gotten Lazy with the miracles:

[Nope]

So if we had complete and total scientific repression and were a population of filthy nomads who had no doctors of any kind...would god still be able to cure cancer?

Good question, God would have less options with their healings, but yes he would still be able.

But people who don't believe also are healed so their prayers didn't work in conjunction with god because they didn't say prayers

Because we have a few religious posters who are jerks, I wanted to say thank you Strawdog for being polite and occasionally admitting that you don't have the answer