This might prove to be a time bomb, considering that approximately 95% of theists won't agree with me. Prayers cannot make God change His mind, that's the point. I mean, requesting prayers. That's not simply my opinion but my understanding of Numbers 23:19 in the Torah, where we have that God is not like a man to change His mind.
Prayer, by definition, if we seriously think it through, is an attempt to make God change His mind. I mean, as far
as requesting prayers are concerned. When we pray about something that is missing in our lives, whether in the health sector or something similar, we are simply trying to make God change His mind from the state of ignoring our condition or of being unaware of it into becoming reminded of something that has gone wrong with creation.
Now, allow me to bring into your attention that this thread is not meant to vandalize with the building blocks of faith throughout generations of mankind's existence on earth. But if we are to pray for another who is ill, for instance, it might be effective, but we must let him or her know that we are doing so; otherwise, nothing will happen. Even if we forget it or change our mind, it will be good for both the praying agent and the one we are praying for.
In conclusion, there are three different kinds of prayers: Requesting prayers, thanksgiving prayers, and song prayers. Most Jewish prayers are made by way of songs. But both thanksgiving and song prayers are very salutary. The only problem is with requesting prayers, which implies the pretense to change God's mind. This only causes anxiety. Thanksgiving prayers are good to preserve a happy spiritual mood; and song prayers contribute to elate one's heart into a condition of happiness. The Psalms are of the song kind. Hence, at the rivers of Babylon, when asked to sing, the Jews would decline on the basis that they could not sing songs of Zion in a foreign land. (Psam 137)
Mark 11:24: Therefore I tell you, whatever you ask in prayer, believe that you have received it, and it will be yours.
Matthew 7:7: Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you.
If the way everything happened was already God's will, then religion itself that has changed so much over the millennia wouldn't exist in the first place. The existence of religion requires us to believe that God changes his mind, unless we are resigned to believe, after picking the religion of our choice, that God didn't exist before that religion.