What always irritates me is when someone describes a a really horrible crime, committed by someone claiming to be a believer, then uses that as their proof that not only is there no god but anyone who thinks there is must be at least borderline criminally insane!
Or contrarywise, someone who prays and recovers from an illness and uses that to prove the existence of God or the efficacy of prayer.
It is silly. And pagan.
So you don't believe in miraculous recoveries? What about miracles?
Frankly asking God to be healed smacks of paganism in the first place. And can lead right to paganism: I'll do this, if You do this. And folks can pile on Orthodox traditions which look just like this. And well those would be pagan.
Or worse yet: this person was "healed" because they are "special". What about those who ain't?
See the Lord's Prayer and I challenge you to find something that looks like a request from God materially. (That bread ain't bread).
The Christian approach to such things is of course the human reaction to want to be healthy, happy, wealthy, and wise (we are fallen), but
Thine not mine is the essence. Jesus Christ himself did not wish to die and prayed to be delivered, but again only according to the Will of the Father. So to pray for things as such, ain't so bad. But if that is the bulk of prayer, I would be concerned.
And if you are healed, then as St. John Chrysostom says (paraphrased)
it is to suffer more for the Glory of God. To much is given, much is asked, and all that.
And certainly, you ain't gonna convert a halfway intelligent atheist to become a Christian because someone's cancer went into remission after visiting an icon.
In short, it would seem to me that the essence of Christian prayer is the Lord's Prayer:
God is worshiped.
God is thanked as the giver of
all things, all of which are good (whether we think so or not).
God is asked that He keep offering all those gifts according to His Will.
God is asked that might endure all those gifts to His glory, with a specific plea for partaking in the Eucharist to better endure, love, and know His Will.
God is asked for forgiveness for all things done and not done by us to His Glory to the measure we do the same for others.
God is petitioned not to send to us what would damn us.
Something like that.
Not:
God please take away my cancer. I am so sorry for how I have sinned. And so on.
More:
God please give me the strength to witness to Your Love and Glory whether in health or sickness.
Then you can add in whatever natural human self-centered stuff we need to. But the above is what is of the essence.
Or so I have been taught.
Anything we get is a "miracle", as we deserved nothing in the first place.
Pagans bargain with God for they want.
Christians worship God and thank Him for whatever they have and the strength to witness to Him, whether cancer or winning the lottery.
Of course, I could be wrong.
I am sure others can correct me.