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
This is a personal question, which means that only you can answer it. However, I can give some examples that might help guide your work.
An example of a primary source that you might encounter in your own life is that of a news article. As this article is likely to be written by a reporter witnessing the events, it can be considered a primary source. On the other hand, an example of a secondary source would be a non-fiction book that talks about a historical event. This is because such a book would give a second-hand account of an event based on historical information.
Technically, yes, it is true that the development of the middle class signaled a decline in the importance of nobility, since people were able to have more economic freedom.