If you go around to a random group of people asking the question: "What is prayer?" the most common answer you will get is: "Asking for something" (either for yourself or for others). This is followed fairly quickly by all sorts of questions, centering around the concern of "Does it work?"
I've been involved in that dynamic myself any number of times over the years, and once had a fairly large spiritual crisis over it. I've talked to lots of people about this and been on both the giving and the receiving end of the conversations. The result of that over many years has been to learn that this whole approach isn't really the heart of the matter.
Last night I got a call about a very old and dear friend who is away on a trip and has been caught in a remote area with what may very well be a heart attack. When I got the call they were trying to get the local Emergency Response Team in to her, with the expectation that they would call a medical helicopter to evacuate her to a regional hospital.
My response was immediate: I must pray. And the second response was just as strong: I must get other people to pray. I made some telephone calls to mutual friends and wrote several emails to people who would want or need to know. I gave them the news, but that was really a vehicle for asking them to pray. I never stopped to consider what the result of the prayer was going to be or how likely it was that God's mind was going to be changed by these prayers. I was faced with an imperative: the most important thing to do right then was to pray and to get some other people to pray. The issue, in fact, was not the results, it was the relationship.
Then I set out to do a thing or two. One of the questions about praying for others is "how do you do it?" Well, after a short time I almost always find it helpful to do something about my intercessory praying.
I went to our Church and lit a candle and stayed there for a bit and prayed. I find candles very compelling, and anyone around here can tell you that I'm always lighting them. Again, the question is not results, it's the imperative. Where I'm faced with a dark situation, my instinct is to put some light in there - it's that instinctive. And I like knowing that when I'm done with praying by the candle I can leave, and maybe my attention and my prayer will wander, but the candle can go on carrying my prayer, even when my unreliable mind goes off somewhere else.
Then at Compline I found myself involved in prayer in a way that I haven't been in quite a while. The hymn we sing at that Office is a sort of lullaby. Wikipedia defines a lullaby as "a soothing song sung to children as they go to sleep". That works well enough, except that the 'children' part is too restrictive. Why just children? I used that lullaby for my prayer. I mentally made a cradle with my arms and put my friend in it and sang that hymn to her and for her:
"To you before the close of day,
Creator of the world, we pray,
that in your mercy you will be,
our guardian and security."
And that was my prayer - rocking my friend while I sang to her. I'm always inventing small things like that which I can do for praying when the mental issues ("How is she?", Will she get better?", "Is this working?") are unanswerable or beside the point. I need to do something for the person I love,and that something has to involve her and me and God. So I invent ways to pray. It's a straight line relationship. I light candles, I sing lullabys, I do God knows what. There are no mental negotiations involved at this point. There is a friend. There is need. I must pray. That, for me, is the real issue about intercession.
The monk Thomas Keating, who is the father of the meditation practice called Centering Prayer, describes Centering Prayer as sitting in the presence of God with the intention of consenting to whatever transformation God is working in me. That is exactly what I mean by intercession, except that it involves more people than just me. I sit (stand, walk) in the presence of God with whoever I am praying for. I lift that person to God - and the candle or the lullaby are just ways of lifting that person to God - and then I consent to whatever transformation God is working in our lives.
Does it work? Of course it works. It involves God and me and the person I'm praying for, so of course it works. But who knows what the result will be? God is always and at every moment at work, and what I'm doing is consenting to what God is doing in me and in those for whom I pray. The energy of that consent is my prayer. And that way, my prayer is a lot bigger than anything I can wish for.
A number of years ago I was really converted back to the practice of Intercessory Prayer in the course of a visit to the nuns at Burnham Abbey in England. Their life revolves around intercession. In those days at least, there was a prayer desk in the middle of their choir, which held all of the requests they had received for prayer. One of the sisters was there all the time, 24 hours a day. One of them kept a vigil from 12 to 3 at night each night and the rest of the community had an hour at a time during the rest of the 24 hours. That was their ministry. They are cloistered and they don't go out to minister. Instead they minster all over the world, by their intercessory prayer.
The sisters didn't explain their prayer to me or try to persuade me with arguments or anything like that. They just talked about their prayer very simply and very shortly. It was totally convincing. It hadn't anything to do with arguments. It was what they were, not what they said. Just seeing them there, kneeling at the intercession desk, was enough to convince me that they were absolutely authentic. That was the beginning of my return to intercession, and my journey to figure out how I was going to do it.
It really is a matter of relationship, not results. Everyone who has prayed for a while knows that there can be what we call "results". We also know that whether or not there are going to be results is always a mystery. And it always will be. It's because of the nature of relationships. If you start concentrating on whether a relationship is giving you the results you want rather than concentrating on the other person, pretty quickly the relationship is going to be in trouble. The point of intercession is people and God and the relationship between them and you. Whether or not it "works" is not the point. You might just as well ask whether Communion "works".
Intercession "works" if you have to do it. The "result" is your turning to God. When I got on that wavelength, I began to understand what intercessory prayer was all about.
James Huntington, who founded the Order of the Holy Cross, had a way of coining memorable phrases, and one that stays with me is "We shall probably find no surer test of our growth in the spirit of the cross, and of our Lord's high-priestly prayer before his passion, than a deepening fervour of intercession...." There it is. If your relationship with God grows, your need to pray for others grows. That's one of the few ways you can know if your prayer is actually deepening. As Fr Huntington also said: "Love must act as light must shine and fire must burn.", and part of that acting is praying for others.
The rest we can argue about as we have time. But increasingly my time is taken up not with arguing but with the need to pray.