Can a warrior be religious? Can there be a religious war? Give examples of each.?

Yes and Yes

knights of Malta and you really can't figure this part out?

King David was an experienced and seasoned warrior.

Soldiers have always been Christians. Religion is not distinct from real life and soldiers have the obligation as Christians to obey legal orders. General officers and politicians have the duty to defend the population and make moral decision about sending soldiers to their death and destruction of enemy soldiers and production capacity.

Was is to be a last resort, not the first option to settle disputes that threaten those you have an obligation to defend.

Are you stupid or are you a true.

Are you trying to get Christians to justify your holy war?

Ever hear of The Crusades?

Yes, and yes.

...and no, I will not do your homework for you.