Last year, apostate Hector Avalos gave a talk on prayer:
This appears to be a rehash of objections he raised in more detail in his article: "Can Science Prove that Prayer Works?" Free Inquiry 17 (1997). I'll comment on that article.
The problem with this and any so-called controlled experiment regarding prayer is that there can be no such thing as a controlled experiment concerning prayer. You can never divide people into groups that received prayer and those that did not. The main reason is that there is no way to know that someone did not receive prayer. How would anyone know that some distant relative was not praying for a member of the group that Byrd had identified as having received no prayer?
I basically agree with that.
For example, many people with high blood pressure would call me to pray for them when their blood pressure rose. I would come and pray, and afterwards the blood pressure would fall. This would be regarded by me and the patient as an answered prayer. Yet most blood pressure frequently does rise and fall on its own because our bodies have systems that function like the thermostat in our homes. Many other "sick conditions" also get better on their own because the body has mechanisms to relieve itself (for example, fevers, colds, many types of aches and pains).
Another reason for the widespread belief in divine healing among Christians, especially Pentecostals, is the dynamic of the services in which healings are said to occur. In many instances a great quantity of healings are reported by traveling evangelists. Usually the evangelist asks the patient what the problem is.
Many may say, for instance, that they had a "kidney problem" when they have a backache. The evangelist usually does not verify if the patient is indeed suffering from kidney problems and is not usually familiar with the patient s medical history. Yet he might announce that the patient was healed of "kidney problems" to the entire audience. The evangelist also might assume that the persons who approached the altar were healed, and so he may report that multitudes of persons were healed in his previous stop. Indeed, the evangelist rarely performs follow-up examinations. Thus exaggerated numbers of reported healings can multiply rapidly in these environments.
The psychology of the petitioner is also a contributing factor. If the evangelist, for example, asks patients if God has healed them, they are very likely to say "Yes," even if their symptoms say the opposite.  The reason is that many patients are embarrassed to say that God has not healed them because this appears to insult God.
i) I agree. However, citing unimpressive examples does nothing to counter more impressive examples. What about medically verifiable miracles?
ii) Avalos fails to draw an elementary distinction. If you wish to prove the occurrence of answered prayer, then it's logical to begin with unambiguous examples. But once you establish the occurrence of answered prayer, that makes another examples more likely to be cases of answered prayer, even if they are ambiguous.
For most of my young and adolescent life, I was a faith healer in a Pentecostal tradition. I witnessed what I then thought were resurrections, spontaneous growth of short limbs, cures from cancer, and many other types of diseases. In retrospect, I have learned much about why people believe in answered prayers even when there is evidence to the contrary or even when it is logically absurd. Every single case of a supposedly answered prayer that I witnessed can be explained by one or more of the following factors: (1) false assumptions, (2) erroneous information, and (3) wishful thinking.
Yet he admits that he "witnessed what he then thought were resurrections, spontaneous growth of short limbs…" He fails to explain how he could misperceive the instantaneous growth of short limbs. That would be a visible phenomenon, right? Does he think his eyes played tricks on him?
For Christian believers, answered prayers qualify as a type of miracle. According to Charles Hodge, the famous American fundamentalist theologian: "A miracle, therefore, may be defined to be an event, in the external world, brought about by the immediate efficiency, or simple volition, of God."  The problem with verifying scientifically that miracles as defined above ever occur is that the Christian god is supposed to have infinite characteristics, and we can never know whether a prayer has been answered by a being that is said to be infinite.
Let me explain. One of the infinite characteristics of the Christian god is omnipresence - that is, this being is said to be everywhere in the universe at the same time. The Christian god is also said to be eternal, all-powerful, and all-knowing. Yet, we, as finite human beings, could never know that such an infinite being exists. For example, in order to know that there is a being who is everywhere at the universe at the same time we would have to be everywhere in the universe at the same time.
i) I don't think God is literally omnipresent. God isn't a physical being. So God isn't everywhere. Strictly speaking, God isn't anywhere.
ii) It's not uncommon to postulate the existence of spaceless entities (e.g. numbers, logical laws, possible worlds). Their explanatory power accounts for concrete states.
In order to know that there is a being who is eternal, we would have to be eternal.
i) That's a one-sentence assertion. He fails to explain why we'd have to be eternal to know there's an eternal being. What's the principle? That you must be like what you know? The subject of knowledge must be the same kind of being as the object of knowledge? Must I be a bumble bee to know that bumblebees exist?
ii) I don't need to be timeless to know that timeless objects exist (e.g. numbers, logical laws,possible worlds). I infer their existence because they do necessary explanatory work. They are indispensable to account for certain concrete states.
In order to know that any event we witnessed in the world was caused by a particular being, we first have to know that such a being exists. For example, it would be absurd to say: "I know my prayer was answered by an invisible Martian, but I do not know if invisible Martians exist." The reason this statement is logically absurd is that it attributes an action to a being not known to exist.
Really? Take white explorers who saw bison on the Great Plains for the very first time. Must they know in advance that bison exist to take sightings of bison as evidence for their existence? Must they have evidence that bison exist independent of bison sightings before they can acknowledge that bison exist based on direct observation? How would Avalos ever establish the initial existence of something? If he automatically discounts the first case on the grounds that we can't accept that evidence unless we already know it exists, then that rules out novel discoveries.
Likewise, in order to know that any event (e.g., an answered prayer or any other supposed extraordinary event) was caused by an infinite being, we first have to know that an infinite being exists. Since we can never know that an infinite being such as the Christian god exists, we can never know that any event we witness was caused by this being. In sum, knowing scientifically that an infinite God answered a prayer is logically impossible.
That piggybacks on a couple of bad arguments (see above).
Prayer would be unnecessary if there were an all-knowing, all-good, and all-powerful God. Let's suppose that the most gifted doctor in the world happens to be your friend. This doctor has the ability to cure any sickness known to modern medicine. Let s also suppose that this doctor is living with your family, which includes a six-month-old baby.
Now if this infant were to become violently ill in the presence of this super-doctor, what would you expect from him? If the baby is choking, for example, you would expect him to use techniques that will relieve the baby s problem. You would not expect him to ask you first if you believed that he could cure your child before he was willing to help the child. You would not expect him to require you to show how much faith you had in him before he would help your child. What you would expect is for this super-doctor to act as soon as he sees the child choking.
Among other things, prayer is designed to cultivate a sense of dependence on God. If all our needs were automatically provided for, there'd be no appreciation or realization of our dependence on God.
Moreover, we shouldn't just expect people to do us favors. Asking for a favor is an acknowledgement that if your request is granted, the grantor is doing your a favor. Even if a parent knows that his teenager wants something from them, he may wait for the teenager to ask. A teenager shouldn't just take his parents for granted. Receiving what he asked for is a basis for gratitude. Otherwise, the child grows up to be a selfish, thankless person, since he expects everything to be provided without ever having to ask. The same dynamic applies to friendship.
Let's also suppose that this doctor has the ability to prevent cancer in all children anywhere in the world even before it occurs. Undoubtedly, you would expect that if he had this ability then he would use it, if he really fits our definition of "good." But if the doctor has this ability, and does use it, then you would not expect there to be any cases of infantile cancer in the world. If this super-doctor has this ability, then he should not wait for anyone to ask him to prevent the suffering of children with cancer. We would expect him to act immediately out of pure goodness.
That depends on the long-term consequences. Individual lives are not self-contained events. Rather, they have short-term and long-term impacts on other people's lives, for better or worse. Suppose God heals a child with cancer. Suppose his future grandson is a security guard at an oil refinery. He works the nightshift. One of his duties is to periodically check the gauges to make sure a system isn't going critical. But instead, he's watching a skin-flick. As a result, the refinery explodes, incinerating the inhabitants of the company town. Saving one life resulted in a thousand deaths.
Similarly, an all-good God would not want anyone to suffer.
Some people deserve to suffer. Take people who commit atrocities.
An all-knowing God would know who would suffer ahead of time, and an all-powerful God could prevent suffering before it happens. Thus, if there were an all-good, all-knowing, and all-powerful God, then there would be no need for prayer in the first place, especially if the prayer is used to alleviate illnesses or any other type of suffering.
Of course, that's the problem of evil, for which there are different, sometimes complementary, theodicies. For instance, suffering can be a theater for soul-building virtues. Likewise, a world without suffering will have a different set of people than a world with suffering. Each scenario has tradeoffs. Each scenario has winners and losers.
Even if someone prayed to the Christian god for healing and that person was healed, it would not prove that the healing was done by the Christian god. All religions claim to have answered prayers. For example, according to the Bhagavad-Gita, part of the sacred scriptures of Hinduism, the god Krishna claims that it does not matter which god human beings worship; it is Krishna who answers their prayer.  Thus, it would not be scientifically possible to show that it is the Christian god who answered a prayer even if such a prayer was answered.
i) Avalos is equivocating. He's an atheist. So even if you can't prove that a prayer was answered by the Christian God, it still falsifies atheism.
ii) What kind of god is Krishna? He didn't always exist. He had parents (Devaki, Vasudeva). Is it even possible for an anthropomorphic deity like Krishna to exist? Is it even possible for a finite god like Krishna to answer prayer?
iii) Hector's comparison is reversible. If the Christian God intended for Ravi Zecharias to exist, he might answer a prayer to Krishna by one of Ravi's ancestors, in case Ravi's future existence is contingent on that answer. Likewise, if God intended Tom Schreiner to exist, he might answer a prayer to Mary by one of Schreiner's Catholic forebears, in case Schreiner's existence is contingent on that answer.
iv) There's a conspiratorial quality to Hector's objection. For instance, he teaches at Iowa State U. Now it's hypothetically possible that Iowa State U is really a front organization for a drug cartel. This deflects attention away from the cartel's nefarious activities. They bought off the local reporters and politicians to avoid detection.
Hector's habit of floating hypothetical alternatives is a diversionary tactic. Even though it's hypothetically possible that things are not as they seem, unless we have actual evidence to the contrary, it's irrational to be suspicious.
Even if we saw an extraordinary healing occur (e.g., a severed leg grow back instantaneously), we would not be able to prove scientifically that it was a supernatural occurrence. To say that something is supernatural is to say that something is not natural. But to say that something is not natural, one would have to be practically omniscient because that would be tantamount to saying that we know all the natural factors that could possibly be responsible for an event, and are claiming to know that none of the factors was responsible. No one has the kind of knowledge, and so consequently no one could ever call anything non-natural.
The most we could say about an event whose cause is unknown is that the cause is unknown. As already noted, we would be less justified in attributing an extraordinary event to an infinite being.
But even if you recovered from a potentially deadly illness in some unexpected manner, you still cannot know if it was an act of God. The most we could say is that the recovery was accomplished through an unknown process. Many recuperations that may appear supernaturally miraculous may be due to very natural processes which have not been recognized or studied previously. Indeed, one can draw up a long list of phenomena that were unknown 100 years ago but are deemed perfectly natural today. In fact, most believers in prayer have received conventional medical treatment, and so one cannot eliminate the possibility that it was the medical treatment, not the prayer, that actually had a beneficial effect, even when such an effect might be unexpected.
i) That argument either proves too much or too little. We can turn it around. You'd have to be omniscient to disprove God's existence. You'd have to be omniscient to rule out supernatural factors. As he himself says, "there is no way to know that someone did not receive prayer". So naturalism is unverifiable.
ii) By that logic, every biblical miracle might have happened, just as people saw it occur, yet it has a naturalistic explanation. Surely Avalos doesn't take that seriously.
iii) If he really takes that position, then he's a secular fideist. If nothing in principle could ever count against atheism, then atheism isn't based on evidence. Atheism is indifferent to evidence. Faith-based atheism rather than fact-based atheism.
iv) If a Christian receives conventional medical treatment, that explains the instantaneous regeneration of an amputated limb?