It is called freedom of religion and freedom of speech.
The oft revered Authorized King James Version (KJV) of 1611 was itself a revision and consolidation of the work done by William Tyndale, who did a series of translations from the original languages starting in 1522. But the archaic nature of the William Shakespeare version of English, for which the 1611 version of the King James Bible is based, demanded revision. Today there is a New King James Version (NKJV), dated 1982, in which the work for it started in 1975. In the mean time, there are a number of versions that are popular: New American Standard, NASB (first edition 1971, latest edition 1995) which is based upon the 1901 "American Standard Version"; the New International Version, NIV (1978, 2011); and others. The point being that there are a number of versions from which to choose. Why?
The WIKI says this about the NASB:
"Seeing the need for a literal, modern translation of the English Bible, the translators sought to produce a contemporary English Bible while maintaining a word-for-word translation style. In cases where word-for-word literalness was determined to be unacceptable for modern readers, changes were made in the direction of more current idioms. In such instances, the more literal renderings were indicated in footnotes.
"The greatest perceived strength of the NASB is its reliability and fidelity to the original languages, which, along with other literal translations, also allows for ambiguities in the text's meaning. Its corresponding weakness is that its readability and literary style sometimes prove confusing to the average reader. In addition, its printing of verses as individual units instead of paragraphs makes the text appear fragmented (though more recent editions are available in paragraph format)."
The WIKI says this about the NIV:
"The roots of the New International Version began in 1956 with the formation of a small committee to study the value of producing a 'faithful translation of the Scriptures in the common language of the American people.'"
Some translations are considered as "theologically liberal", like the Revised Standard Version (RSV), which includes the Catholic Apocrypha. The New World Translation (NWT) is the sole bible version produced and used by Jehovah's Witnesses and is considered an intentional perversion by evangelical Christians for purposeful changes to scripture in order to validate their beliefs. A common example is the insertion of the article "a" before "God" in John 1:1 in order to diminish the clear description of Jesus (i.e., the "Word", ref. verse 14) from being God to "a God". Hence, Jesus becomes not equal with the Father – the fundamental precept of JW’s and vehemently rejected by evangelical Christians.
Fortunately, the avid Bible student has the ability to compare versions of the Bible. For example, the "biblehub.com" website provides parallel access to 23 translations, but does not include the RSV and NWT, probably for reasons cited. The original language is also available so that complete passages and single words can be looked up to see from what the translators were working. Biblegateway includes 46 versions!
Obviously, the availability of versions confuses people. Here is a tip: the KJV, aside from the Catholic version, was the only version available for English speaking people for about 300 years. Now there is a newer version, the NKJV, that has some minor criticism but is available to people who view Shakespeare's English too difficult to understand. And the NASB and NIV are also good translations. Go to "biblehub" or "biblegateway" and compare versions and convince yourself.
We are truly blessed in this day and age to have this amount of resources and tools for studying God's Word. But with that richness comes some complexity and decision making.
By the way, the translation, while the main part and focus of the Bible itself, is one part of a reason to select a Bible for personal reasons. Various publishers, like Oxford University Press and Zondervan, provide an “envelope” to several versions that includes a tremendous amount of useful study material and help: maps, commentary, character profiles, historical background, etc. I recommend the Scofield and Life Application Study Bibles.