Why religious extremism increase Worldwide?

Nowadays every country have facing a big problem religious extremism.why religious extremism increased.the main factor involved in religious extremism is political parties.they have religious wings and promote there's religious thoughts not for sake of God but for vote bank,funds,keen interest .they criticized other religions,compelling them to leave his religion and accepts there's religion.How to reduce it?we must promote humanism insisted of religionism on local as well as government levels , must protect fundamental rights of every individual and equally treated.