On the sovereignty of God: do prayers change God's will?
I'm sixteen and one of seven children. A few weeks ago, we found out that my fourteen-year-old sister had a brain tumor, which was then successfully removed. However, it was cancerous and she has to undergo treatment (chemotherapy, etc) soon. Obviously I've been really upset.
Lately I've been thinking a lot about the different outlooks on free will and God's sovereignty. For the first time ever, Calvinist ideas have made at least some sense to me. This isn't exactly the question I have, but it's probably some good back round info.
Ever since this happened, I've been praying a lot. We have so many friends praying for us, and people keep reminding me how powerful prayer is. Despite this, I've had so many doubts. If I don't pray enough, will God not save my sister? Do my prayers really change God's mind/ will? I then thought of the story of Jonah "When God saw by their actions how they turned from their evil way, he repented of the evil he had threatened to do to them; he did not carry it out." (Jonah 3:10). But does God create evil? Evil is the absence of good, and is so opposite of God, the one, the true, the good, the beautiful. Does God send suffering? My sister said that she thinks that God sent this because he knew my sister and our family could handle it, and that this is a way of his bringing us to him. And it's true, so many people now are praying who have never prayed before, and I'm touched.
But I really just don't know what to think. I've always thought that terrible things simply happen because of the fall, and God gives us the grace to cope with it. Now I just don't understand: does God cause evil? Does he make children suffer in order to win people to him? Do my prayers even matter? Does his mercy depend on what we "pay" him in prayers and sacrifices?
All this time I've felt so angry at God and I've wanted to turn away from him, but I can't seem to do it. I think that it is him bringing me to him, but I don't know how to put my trust in him, because I am afraid he will take my sister.