What if intercessory prayer worked? What if, when you or someone else had a disease, and you prayed, there was a significant chance that the disease would be healed, either by one or another divine being, or by some other mechanism?
And yes, I realize that a lot of people think that it does; but I’m going to look at this in the way a science fiction writer might, and see what happens.
One of the most obvious attributes of prayer is that it’s cheap and easily-accessible by anyone. It’s also said to be as safe and side-effect-free as, say, homeopathy. That means that it should be everyone’s first recourse, not their second, third, or last. People wouldn’t say “there’s nothing to do now but pray” after an operation; they’d say “prayer didn’t work; there’s nothing to do now but operate”.
Insurance companies would refuse to cover the cost of, say, blood pressure medication or chemotherapy unless you’d already tried cheap prayer first. In this, they would be joined by doctors, because medications have side effects (to say nothing of surgery and similar operations), so it’s best to try side-effect-free prayer first.
Then again, maybe insurance companies wouldn’t bother: they’d just assume that everyone would pray before resorting to medical professionals, that there wasn’t any real money to be saved by screening out the vanishingly few die-hard antitheists, and they’d get rid of that particular bit of paperwork.
At the same time, though, assuming that not all prayers are equally effective, we’d see a new profession: prayer therapist. These would be people whose job it is to help you pray in the optimal way: do you need to be on your knees, or can you just sort of wish for recovery while sitting in traffic? What are some good ways to achieve the purity of heart that gives the best odds of recovery? Is it okay to take painkillers so you can pray without being distracted by the pain? For that matter, are Catholic prayers more effective than Buddhist ones, or doesn’t it matter? (Yes, it means that some people would stay with insurance companies that they hate simply because their favorite prayer therapist is in-network.)
Naturally, in addition to the well-informed professionals, there would be the fakers, posers, and spouters-of-BS. Hollywood celebrities would hire celebrity prayer therapists and would compare notes on morning talk shows about the latest trends and fashions in intercessory prayer.
None of this even addresses the wider theological repercussions: if prayer really worked, there would be an awful lot fewer atheists, and a lot more members of whichever faith had the most effective prayers. I’ll leave it up to the reader to decide how well this little flight of fancy corresponds to the world we live in.