What purpose? The main reasons that the translations differ is because of different theological views, and because of large discrepancies in the best texts we have remaining. John Mill studied 100 New Testament manuscripts and found 30,000 discrepancies. Bart Ehrman, commenting on this, noted that there are more contradictions between the all manuscripts we have than there are words in the New Testament. So there is a lot of ambiguity here, which lends itself to different translations as one wishes
You do have translations like the New World translation where they are distinctly one sided and you have things like Luther putting the word, "alone" in his translation but in most cases there are a ton of other variables. Most common is how to best translate a verse.
Let's say that today I write down, "I hoofed to the mini-mart to buy a pack of camels."
A thousand years from now various translators want to translate that verse so that it can be understood by the people of the day. You could do a literal translation but the problem is that the people in the future would completely misunderstand what is being said because of the nuances of an old language. Literally translated they would think that I rode some sort of hoofed animal to to some sort of market to buy a bunch of hump backed four legged fauna.
So one person translates it as....
"I walked to the gas station to purchase a container of cigarettes."
Another translates feels that the current population might not know what cigarettes are since they were outlawed centuries ago and most haven't heard of a gas station now that cars run on the sun. He translates it as...
"I walked to the small market to buy a package of leaves wrapped in paper for the inhalation of their narcotic smoke."
Was that done for differences in theology? No. At times and in certain verses it happens but on the main this is not the reason why one translation differs from another.
As far as discrepancies. It depends on what is meant by discrepancy.
If one old translation says,
"I walked to the minimart to get a pack of camels."
"I drove to the minimart to get a pack of camels."
"I walked to the minimart to get a pack of Winstons."
While there are differences in the text it really isn't all that concerning.
Now if one said....
"I walked to the minimart to kill a man."
That is a concerning discrepancy in the text.
Certainly there are some pretty large discrepancies in even the texts that we accept today. The nativity scene is a great example.