Many religious people believe that their god can heal them. A speaker for the Healing on the Streets (HOTS) Bath in the UK for example says that "Christians believe in, pray for and experience God's healing". "We're Christians from churches in Bath and we pray in the name of Jesus. We believe that God loves you and can heal you from any sickness".
They began handing out flyers that read:
Need Healing? God can heal today! Do you suffer from Back Pain, Arthritis, MS, Addiction ... Ulcers, Depression, Allergies, Fibromyalgia, Asthma, Paralysis, Crippling Disease, Phobias, Sleeping disorders or any other sickness?..."We'd love to pray for your healing right now!"
The Advertising Standards Authority (ASA) in the UK concluded that the adverts being made by the (HOTS) - Bath were misleading.
I have read of an experiment conducted by a religious organisation to prove that prayer works in healing but caused them embarrassment when they found that prayer had a negative effect instead ( which some jokingly attributed to a performance anxiety effect caused by patients knowing that they were being prayed for).
So far, I am not aware of any experiment or study done on a large scale proving that prayers do heal. You can easily find articles dispute the methods of such experiments but none offered a way in which such experiments can be improved. Most simply finish off by saying: "Well the healing power is beyond science's ability to measure anyway". In other words, there is no scientific evidence for prayer's power to heal.
[If you know of any study or experiment that proves either way, please share.]