Why is God so cruel to His own creation?

Why does He allow people to make war, have diseases (like Cancer), and sorrow? generally every human lives in fear, desperation, confusion and pain..Why does God allow this to happen to people? If he really loved us, wouldn't he just let all people go to Heaven instead of allowing people to suffer here on Earth, and then sending many people to burn in hell forever and ever, until the end of time?