A religious believer might not go to war because their religion is against hurting anyone, killing anyone and making people suffer.
Just war is:
-Legal
-Happens for a reasonable cause
-Civillians must not be used
Holy war is war which happens for religious purposes, for example if Muslims and Christians were fighting over holy land- that would be holy war.
Holy wars usually have three elements:the achievement of a religious goalauthorised by a religious leadera spiritual reward for those who take partAn example of holy war are the Crusades
References: BBC Bitesize
