Amen, the very last word in the Bible, could well have begun as a Pagan word.
Yet Christians, Jews and Muslims invariably end their prayers, scripture readings, and hymns by saying Amen as an expression of concurrence.
They also say it to acknowledge their agreement or reinforce a statement that another person has said.
From old Egyptian texts we can see that people regarded the Sun as the emblem of the Creator. They called the Sun Ra, and all other gods and goddesses were forms of the Creator.
One of these gods was Amen; a secret, hidden and mysterious god named variously Amen, Amon, Amun, Ammon and Amounra.
For the first eleven dynasties (c. 3000-1987 B.C.) Amen was just a minor god, but by the 17th dynasty (c. 1500 B.C.) he had been elevated to be the national god of southern Egypt.
This position gave Amen the attributes and characteristics of the most ancient gods, and his name became Amen-Ra, that is, a supreme form of God the Creator. By the 18th Dynasty (1539-1295 B.C.) a college had been established to study Amen-Ra and as a focal point for worship
So Amen was originally the name of a Pagan god, who was considered a form of God the Creator. But he was certainly not considered God, or Christ.
Interestingly, most Pagans today tend not to use the word, preferring instead to say "So mote it be", an old Anglo-Saxon term.
Indeed, in the Bible we see Jesus Christ referred to as "The Amen". Christ is God's Amen to all that he has spoken.
Thereby the name used for an old Egyptian god is replaced by the same name used for Christ.