Just about every religion or belief tries to make history conform to the teaching of their doctrine. Pagans, Christians, Muslims, and even atheist groups are guilty of it. Besides the ethics of it how much harm does it do to a society? How do we put an end to it?

That all depends on what specifically you are talking about. What instances do you mean by changing history? For instance, back in senior year English we read the Tale of the Rood, which was basically missionaries conforming the story of Christ's crucifixion and subsequent death so that the Gaelic people they were trying to convert would be more receptive to Christianity, i.e. they changed the story around to make Jesus sound pretty B.A. In the story Christ nails himself to his cross which is made of gold and adorned with jewels, none of the soldiers touch him, he doesn't wince in pain, he calls his followers soldiers etc.

History doesn't change. But our understanding of it does.

I have been going back to the original documents for descriptions of many important historical events and comparing them with more-recent descriptions to see what the discrepancies are. An amazing amount of history is known from just one or two people's writings. The William Wallace (Lord Protector of Scotland) story is know from the account of just one person: a minstrel named Blind Hary collected the stories of Wallace's exploits about 20 years after the fact. That's the only account we have from the Scottish side of the story. Caesar's account of the Gallic Wars is the only one we have on that subject. The list goes on... In these cases, we have to take the word of the original chronicler if it seems at all reasonable. But sometimes it doesn't seem reasonable.

People are storytellers and there has been a lot of "drfit" in the re-telling. Perhaps some of this is intentional, but a lot of it isn't: the story gets changed to make it more interesting, to improve the story. This is how legends are created - storytellers improving history.

Archeology and other fields shed light on historical events: A mural found in the ruin of Akratiri on Santorini shows an unknown harbor that matches the descrpition of Atlantis. Geology tells us that the picture is that of a volcanic cone rising in an old caldera. Dendrochronology tells us that there was a world-wide chill in 1629-1625 BC. The Bible tells of plagues of darkness and burning hail falling from the sky. Ipuwer describes a great calamity sometime in the Second Intermediate Period. The 13th Dynasty ended suddenly "about 1640," while the 17th Dynasty, located 400 miles to the south, survived. Is the unknown harbor Poseidon? Have we found Atlantis? Are the Plagues of Egypt true? It looks like we may have to re-write some history.

At Jericho there was a wall, but it collapsed. One analysis places the collapse at about 1500 BC, while the other places it about 1140 BC. Whichever version turns out to be correct, it will have an impact on how we interpret the Bible.

Archeologists report finding no evidence of large-scale encampments in the Sinai. The spring at Hazeroth (where the Israelites camped) has only 42 house/camp sites. Tell Masos (the probable location of Kadesh-Barnea) held, at most, 4000 people. That's not the 603,550 fighting men plus support called for in Numbers 1 and 2. Looks like we need to re-write that part of the biblical account.

Responsible archeologists and historians try not to slant their analyses, but let the data lead them to their conclusions. Inevitably, some of those conclusions will conflict with established legends. That is not unethical; rather, it is the exact opposite. Far from discouraging the practice, it is the only responsible thing we can do.
Doug

history is ones story , so much is conjecture, I think the way its taught is a great place to start... in my sons curricula before any historical data, it shares how they came to accumulate the information, surprising ly we see over and over they really don't know .. often historians look for patterns and create storys around that..understanding that, often history tells the victors side its an important detail ..I like the way we are moving in the way of educating our future...the same is applyed to religon also we give all the data and let them decide what things mean to them if anything, it is amazing what kids say wehn asked what do you think now that you have all the data......We are movng towards a time when free thinking and critical thinking will be main stream instead of so limited as it is now.... we are teaching kids how to think now, instead of what to thnk.. thanks to some great minds in the educational arena... these are exciting times Dark IMO....

It doesn't harm society if the teachings are pure....We could all become Unitarian Universalists?