Is Allah really the most merciful?

The Quran says that Allah is the most merciful, but it seems that human beings are more merciful than him. When people on earth do crime, they are sentenced to prison, even though the conditions are not the best, they are still take care of. Torturing prisoners is illegal. But when we do bad things, Allah wants to BURN US FOR ETERNITY. Is that really merciful. In addition to that we are supposed to be hammered in the grave too.