A Hebrew word meaning “so it is” or “let it be.”
Amen comes from a verb meaning “to be firm or sure.” Some translations of the Bible always keep the Hebrew word "amen" in the text. Others translate it with a statement such as “truly” or “I tell you the truth.” Some translations omit it altogether. Because of its use in the Old Testament, “amen” was also used in Christian worship and religious writings, including the Greek New Testament.
Amen in the Old Testament
“Amen” has much more significance than being the last word in a prayer. In fact, that practice is not shown in the Bible. Saying "amen" at the end of a prayer was not common in ancient times. In the nearly 30 times it is used in the Old Testament, “amen” almost always occurs as a response to what has preceded. When someone says it as a response, it is as if what had been said were their own words. For example, in Deuteronomy 27:15–26 (where “amen” appears 12 times) the people responded with “amen” after each statement of a curse directed toward those who disobey God.
Similarly, “amen” is used as a response after statements of promise or praise and thanksgiving (Jeremiah 11:5; 1 Chronicles 16:36). It was also used as a conclusion to the first four of the five “books” of Psalms (Psalms 41:13; 72:19; 89:52; 106:48). The only exceptions in the Old Testament are two occurrences in Isaiah 65:16. There, the phrase “the God of amen” or “the God of truth” stresses that God is the one who is “firm.” God is completely trustworthy and faithfully fulfills his promises.
Amen in the New Testament
The use of “amen” as a response to a preceding statement is continued in the New Testament letters and the book of Revelation. It appears after each of the following:
Doxologies or statements of praise (Ephesians 3:21)
Benedictions or statements of blessing (Galatians 6:18)
Giving thanks (1 Corinthians 14:16)
Prophecy (Revelation 1:7)
Statements of praise (Revelation 7:12)
From 1 Corinthians 14:16, it is clear that a response of “amen” after a statement of thanks was a means for worshipers to participate by showing agreement with what had been said.