There has been debate about whether human is radically evil， good or somewhere in between. For this issue， Kant has made deep researches and put forward his own opinions. He presented that human nature could be classified into three innate good and three propensities to evil in different levels， which co-exist in human nature. That means ‘even the best one could infer an evil disposition’. He elaborated ‘what was human being from religious perspective， intending to make religion rational， pure as well as moral. Kant saw morality as the ground of religion， urging people to fight evil nature to become a better man. In addition， moral-based morality and happiness are supposed to be combined for moral perfection. Accordingly， morality is the utmost goodness and is regarded as the extreme condition of our pursuit of happiness. Therefore， in Kant’s opinions， this propensity to evil cannot be overcome through god or belief. It is human being’s duty to strive to get human nature ruled by morality. By obeying the moral law， human being can acquire incentives guiding himself on the path from bad to good.