Like almost everything else we make up, it is both good and bad and neither besides! It is a good thing because most of the time it teaches love thy neighbour and encourages a tight community etc.However religion can be used to create strife and hatred! Sectarianism in Northern Ireland for example! Or japaneese suicide bombers in ww2! And even modern ones, from afganistan and stuff! The japanese were told it was a great honour to die for their country, and that they'd become a cherry blossem on a treee in a tmple or something.(not too clear on the details, sorry)
But you see it can be good and bad!