Please try to refrain from the cliche answers like, "because without knowing the past, we can never know the future." I am looking for a little more substance. Thanks!
This is a completely subjective question. Pretty much any answer you give, if justified, will be "correct". Nonetheless...
Religion and culture shape every single aspect of civilization as it existed, exists, and will exist in the future. You cannot separate either of these things from the politics or technological development, etc., because they're entirely ingrained. History... it's not a bunch of random facts, separate countries, clean cut eras and relationships. Every civilization is tangled in with every other, and the development of culture (religion is part of that) determines the development of civilization as a whole.
Culture or "Enculturation" defines the thought process of a person. A group of people with the same enculturated beliefs affect history. For example, think of how many wars have started because of one cultures belief that another cultures beliefs are incorrect.
Religion does not need much explanation. It is obvious to even the most illiterate person that Religion has significantly impacted the human race over the last 2000 years.
With out Religion would science be where it is today? Early on, bad or good, it was the Catholic Church that funded a great deal of scientific research. The earliest institutions of higher learning were established by Religious groups. Harvard, Yale, Princeton in the U.S. alone.
Because those things are what makes us different from other animals... Without culture there would be no (written) history for one. Throughout the history of the world, religion has defined cultures and people's lives. Really, one cannot negate these two things from history...if you did there would be really nothing to talk about. People by their nature aspire to the higher and that is what religion and "culture" is.
religion is NOT important b/c look
they just want u to belief at their religion
8000years ago if u didn't belief christianity they will burn u to death or kill in any way until u die.
u belief in god so waz up with that?
Religion and culture decides how a place runs ] obviously history is important to study, so that we can prevent the bad things that have happened from happening again. But religion and culture define why a city/state/country or even society runs the way it does. Take Japan for example - their culture and religion defined their attitude in WWII when they tortured their surrendered enemies - (it was related to the chivalry and code of honor of the samurai - that surrender is unacceptable, even death is batter) you can see this through some of the things they did - like the Rape of Nanking and the Bataan Death March --- although their culture and way of thinking does not condone such human rights violations, it shows you why they did what they did. Hope that helps.