Your religion means nothing. Your God is fictional and your beliefs are pointless. The higher power that I serve is the only true divinity so your obedience is summarily expected or you can expect dire consequences. As extreme or preposterous as this may sound, some choose to go to battle with ideals like this in mind. The question is where is the rationale in this?

Looking back in history, biblical history to be exact, the first religious war was fought over land. In the bible, the first chapter of Joshua tells of God speaking to Joshua telling him that he and the rest of the Israelites are to take possession of land stretching as far as Lebanon to the Euphrates. In this book, God gave the Israelites permission to destroy any opposition which mainly included the Canaanites in order for the Israelites, his chosen people to have this land. According to my research, God's purpose for this was so that his people would have a land all to themselves apart from the idol worshipping Canaanites. God didn't want the Israelites to bow down before false gods like the Canaanites were doing. With God's help, Joshua conquered this promised land in 6 years and divided it among the Israelite's 12 tribes. Ultimately what happened is that once this generation of Israelites passed, many of their children disobeyed God and started worshipping idols like the Canaanites did.

Concerning the reasons to go to war, St. Augustine is credited as the first person to create a just war theory. This doctrine has four strict conditions which include that the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave and certain, all other means of putting an end to it must have been shown to be impractical or ineffective, there must be serious prospects of success, and the use of arms must not produce evils and disorders graver than the evil to be eliminated. According to this theory, just cause for war can be to recapture things taken or to punish wrongdoers, but the injustice suffered by one party must significantly outweigh that suffered by the other. The theory also directs how combatants are to act in war and in recent years, some theorists have also added a guide on behavior after war which includes that just cause for termination is if there has been a reasonable vindicdation of the rights that were violated in the first place and if the aggressor is willing to negotiate the terms of surrender.

In my research of monotheistic religions, I have yet to come across any religion where the divinity is a God inclined to war. Many would claim the Muslim religion promotes a belief in fighting according to the concept of the jihad. This is a religious duty of Muslims that translated from Arabic means strive or struggle. It is commonly used in the expression "striving in the way of Allah(al-jihad fi sabil Allah)", but this expression can also be thought of in terms of Christians striving to be Christ-like. Considering that in mind, Allah and Christ are seen as peaceful deities. The five pillars of islam are five duties that every Muslim is responsible for and these duties are Shahadah(profession of faith), Salah(ritual prayer), Zakah(alms tax), Sawm(fasting during Ramadan), and Hajj(pilgrimmage to Mecca). Some consider the jihad to be the sixth pillar of Islam, but even if that was so, no other pillar mentions anything resembling war or conflict.

"Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, vengeance is mine; I will repay, saith the Lord." Romans 12:19 KJV. If every biblical reference I have found from Psalms 46:9, Matthew chapter 24, Luke 3:14, to Hebrews 12:14 have all pointed to God being a Lord of peace then how can war be justified? My only answer in this is man. According to Genesis chapter 3, we are all flawed creatures and in our many flaws, we tend to twist and misconstrue words until they are bent to our own desires. So called "religious" wars have been fought and are still being fought over not just opposing ideals, but also over desired land. I further believe that there is no justification for war based on religion because every man and woman has free will and it is our free will that allows us to decide who we serve and how we intend to serve our God. Ultimately, after all the research anyone can do on this issue, it still boils down to an individual's free will on what ideals and beliefs they choose to accept.