Why Won't God Just Give Me What I Want?

Most atheists believed in God at one point, but when they prayed and asked God to save them or their family member from abuse or a terrible crisis and He didn't answer them, in the time or the way they wanted Him to, they soon decided that the reason He didn't answer is because He isn't there!  Most Atheists are very angry with God because of what He didn't do for them. Sadly enough, there are many professing Christians who aren't much different than the atheists. God hasn't give them what they wanted so they are upset, frustrated, and even grumbling against God.  Why won't God just give you what you want if He's such a good God?