we are here in this world because Allah(God) created us and sent us to this world for a limited time...He also gave us teachings that what He want from us to do...at the same time He gave us choice to accept those teachings or not...and gave us brain to understand what is right and wat is wrong...now the person who will believe on Allah and spend its life according to Allah's will, will get the reward after death in the form of jannah and the person who will refuse to accept it and spend its life as he himself want will be punished after death...all of this is very clear and easier for those who have open mind but very difficult and complicated who have decided to not accept it.