Why do you think religion causes so much conflicts and wars in the world when it supposed to promote peace?Maybe because they want to say that their religion is right and the other is not. or is it...

Some religious texts lend themselves to interpretations that might be construed as advocating violence. Certainly the Old Testament is not a work of pacifism, even if the New Testament could be construed that way. Ultimately, though, religious conflicts stem from absolute beliefs, as others have said, but also from the fact that many political leaders have exploited religious ideology to support their less than spiritual goals.

I agree that the utter conviction that one's own religion is the correct religion, as well as an intolerance of other beliefs, is the cause of the kind of conflict you mention. The irony is that many religions profess to honor a God associated with peace and love.  I really enjoyed the poem above, by the way.

A major cause of conflict is the feeling that your way is the only correct way.  We get that in religion, but we also get that in things like communism and Nazism and nationalism in general.  So it's not just religion that causes problems due to intolerance and narrow-mindedness.

Mine's right and yours is wrong pretty much sums it up.  The conflicts between different religions are caused by the different philisophical arguments that each establishes for its own purposes.  Religion is based on deductive reasoning, in which "facts" or axioms are stated, and all else derives -- God made the world in 7 days, and therefore.....etc.  Questioning the validity of the axioms is akin to discrediting someone's fundamental beliefs, so there is conflict.

A poem written in the 1800's on the topic:

Odium Theologicum
by Sam Walter Foss (1858-1911)

Verse I
They met and they talked where the crossroads meet, 
Four men from the four winds come, 
And they talked of the horse, for they loved the theme, 
And never a man was dumb. 
The man from the North loved the strength of the horse, 
And the man from the East his pace, 
And the man from the South loved the speed of the horse, 
And the man from the West his grace. 
So these four men from the four winds come, 
Each paused a space in his course 
And smiled in the face of his fellow man 
And lovingly talked of the horse. 
Then each man parted and went his way 
As their different courses ran; 
And each man journeyed with peace in his heart 
And loving his fellow man.

Verse II
They met the next year where the crossroads meet, 
Four men from the four winds come; 
And it chanced as they met that they talked of God, 
And never a man was dumb. 
One imagined God in the shape of a man. 
A spirit did one insist. 
One said that nature itself was God. 
One said that he didn't exist. 
They lashed each other with tongues that stung, 
That smote as with a rod; 
Each glared in the face of his fellow man, 
And wrathfully talked of God. 
Then each man parted and went his way, 
As their different courses ran; 
And each man journeyed with wrath in his heart, 
And hating his fellow man.

I think it is when politcs gets involved in the sense that political parties or corrupted authority figures use religion to manipulate people to follow or support them.

Another reason I think is not necessarily because of the religion, but because of followers of religions not practicing or understanding their religion properly.  Some can also take things to extreme and radical levels, and take a nationalistic personal right-wing approach.

This topic reminds me of a poem titled "The Second Coming" by WB Yeats. I think all religions have lost their sanctity not because of the religions but because of the people heading them. People related with the religions act like agents to motivate people and join them to their religions. There are some billioners afraid of Hell donate money and these are used for charity not in real sense but to attract people and convert them. The priests and monks have no time to concentrate in re-reading the scriptures but cling to rigid orthox views without any explanations, showing people fear of the consequesnces of Hell and Heaven. In short, people attached with these religions are less religious but more of politicians, businessmen, pretentious. What we see in them is not their real attitude and what is real we don't see. In the name and they all exploit the sentiments of people and terrorise. If we see, all Churches, Masques, temples have billions of money with them, an enterprise with itself. So where to utilise them, they think it better to have religious wars like Jehad and so on to draw the sentiments of people towards religion and to hold to the post of them. The rustic people believe in them and they are ready to kill and die for unseen, unknown Heaven.

Certainly this is the high time for us either to impose ban on them or to have another prophet soon to show us the path to peace and unity with new versions of scriptures.

Today, at Bagram airbase in Kabul, a wild crowd of incensed Muslims is, right now, pumping themselves up for a religious outpouring of destruction and bloodshed. The reason for this mayhem is... somebody accidentally burnt some paper. The paper in question was copies of the Koran, and these confused and self-righteous 'thinkers' believe this paper is so magical that nothing is more important. Now, please understand this distinction, we're not talking about the words, no, no, no, nobody has destroyed the words, the words are safe... no, we're talking about paper. And real people are probably going to be slaughtered in the streets tonight because some trivial paper was destroyed.

And last year, when that woe-begotten, trouble-maker Pastor Jones burned the Koran, the same morally-offended Afghans killed 24 innocent, random people, many of whom were beheaded in the street by mobs. But hey, that's just flesh and blood, right?

Such unstable value judgements can only be produced by religion. Yes, we are a violent species who will fight over almost anything, but only religion can make people so brain-washed that they will kill indiscriminately and truly, truly believe they are much more moral and decent than normal people.

"With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Christopher Hitchens.