About 40 people, over a span of more than 1,500 years, were inspired to write the Bible in primarily the Greek and Hebrew languages. In the Old Testament, most books were written in Hebrew, with some sections authored in Aramaic (e.g. parts of Ezra, Daniel, etc.). The New Testament was authored entirely in Koine (common or unsophisticated) Greek, which was the everyday language spoken by people in the marketplace.
Throughout history those who have translated God's word from one language (e.g. Greek) to another (e.g. English) have made mistakes. Translation itself is a difficult task, as words and their meaning in one language do not usually possess an exact equivalent in other ones. One of the primary reasons a basic understanding of Greek and Hebrew is needed is to verify the accurate translation of text especially, when it comes to determining doctrines.
Additions, deletions, and punctuation mistakes easily creep into any translation. Additionally, it is known some translators succumbed to pressures to translate certain text to agree with already accepted doctrine. One classic example is the translation, in the King James Bible, of the Greek word pascha in Acts 12:4 as "Easter." Translators succumbed to their Anglican views and rendered the word incorrectly. Most modern Bibles correctly use the word "Passover" in this verse.
One author stated the following regarding the problems various translations of the Bible can possess.
"Numerous 'contemporary' translations (of the Bible's Greek and Hebrew words) omit or add words - even whole verses. Some 'translators' have boldly added entire books that were never part of the original, authentic canon. And today's 'higher criticism' has purported to expose so-called 'weaknesses' and 'discrepancies' in the authentic texts, undermining the faith of many." (HBFV, second edition, page vii)
In order to arrive as close as possible to the true meaning of any Scriptural verse, it is critical a basic study of the verse's original language words and meanings is undertaken. Delving into the Hebrew or Greek behind a particular passage is one of the tried-and-true methods for digging out God's truth. Such research can mean the difference between believing a false doctrine and one that is correct.
Christians are told, by the apostle Paul, to prove all things and hold fast to what is good (Romans 12:2, 1Thessalonians 5:21). Doctrine does matter, as is borne out in the New Testament with its many references to 'sound' or 'good' doctrine (1Timothy 1:10, 4:6, 6:3, 2Timothy 1:13, 4:3, Titus 1:9, 2:1, etc.) and to the faith (beliefs) first given the church (Jude 1:3).
Suggested study aids
A concordance is a book that lists all the English words found in the Bible (usually from the KJV translation), the verse they are in, and the Greek or Hebrew word(s) from which the English translation is based. Strong's Exhaustive Concordance, which this site uses extensively, was published in 1890 (several updates occurred since then). We highly recommend purchasing a copy of this classic tool.
Other Bible study aids this site recommends for studying and looking up the meaning of original language words include Thayer's Greek - English Lexicon of the New Testament and Brown-Driver-Briggs Hebrew and English Lexicon. The study of the Greek and Hebrew languages will help you prove what is the good, acceptable, and perfect will of God (Romans 12:2).