So you need to explain both what spiritual and prayer mean and avoid using words like psychological, which have nothing to do with either one.
You claimed that prayer has no psychological benefit. I offered an example where it does. You were the one who introduced psychological impact into the discussion. Your claim was
provably wrong.
Claiming that prayer always works is in effect trying to make that part of the definition of prayer, but it is not providing evidence of particular things called prayer and spirituality, and explaining what they are and how they function.
Spirituality: a realm pertaining to or effecting the human soul or spirit or divine nature as opposed to physical nature.
Prayer: deliberate communication, invocation, or act intended to develop harmony and rapport with a spiritual object of worship; a solemn request for help or expression of thanks to said object of worship.
Now, before you get hung up on whether a spiritual realm exists, when it comes to measuring prayer's efficacy,
it doesn't matter. We're not talking about whether a spiritual realm is real and even provable, we're talking about whether or not prayer does anything. Here are the two questions we can use to measure prayer: Does it do work? Does it do its
intended work (is it efficacious)?
Now, prayer comes in many forms, just like exercise. Some of those forms will do more work than other forms, just like exercise. Praying in my mind alone and telling nobody
does do work; many people who pray report prayer bringing them peace, clarity, or insight. So something is happening. Is it the
intended work? Well, if I pray, I am building rapport with my object of worship, which is prayer's primary intent, so yes, it is
in that part efficacious. Now, if my prayer is a specific request for my object of worship to enact change in the world, then
no, statistically speaking there is no evidence that prayer, by itself, enacts change through divine intervention.
They key there is prayer enacting change
through divine intervention. If someone is sick with cancer and I come to their hospital bed every day and pray with then, there is no reliable evidence that God is going to hear me and heal them as I request. However, prayer
can still enact change through its
own impact on individuals. Me coming and praying with that person helps them feel more connected to me and their object of worship, and provides a form of social and emotional contact that
only prayer can offer. All of this reduces stress in very measurable ways. The action of prayer reducing the cancer patient's stress also enables their healing process. They may get better, they may not-- but prayer is certainly helping in that case, not hurting.
Is it efficacious in the sense that God is stepping in and healing them? No. Is prayer's intent to help? Yes. Is it helping with the healing process precisely as intended? No. Is it helping? Yes. Is it building rapport with the object of worship? Yes. Are prayer's effects measurable? Yes.
I hope that provides sufficient clarity for you.