Simplify the following text for a Grade 5 native English-speaking person.
Original: Citing Buddhist sutras and commentaries , Nichiren argued that the Buddhist teachings were being distorted for their own gain ( see the compilation of Nichiren 's exchanges with government leaders and Buddhist practitioners in `` The Writings of Nichiren Daishonin '' 1999 ) .
Simplified: He is often called Nichiren Daishonin .