"The Bible has been translated, re-translated, copied and changed, so how can we even know what it said in the first place?"
This is a bad question, and the person using it has probably picked it up from The Da Vinci Code or some such. First of all, tell them that Prof. John Charmley of the University of East Anglia, England, one of Britain's leading academic historians, has described Leigh and Baigent, whose writings undergird Dan Brown, as "Fabulists." In other words, serious historians laugh at the ideas in the book.
Second, it shows the questioner has no idea about how we got our Bible. They suppose that each translation is made from a translation, whereas all good translations are made from the original language texts. A cursory study of textual criticism, for example via James White's book The King James Only Controversy, should help here, as it shows that the agreement between copies is staggering. There is something like 5% of variation that is meaningful and viable. There is finally no evidence that it has been changed by anybody, as no-one ever had exclusive control over all manuscripts in all places. The long-running disagreements between Rome and Constantinople actually help here!
So no, we can trust the Bible, and the existence of multiple English translations does not mean that we have no idea what the texts originally said!