Q: "Is Amen' the name of a pagan idol?  Should we refrain from using this word in our prayers and in worship?"

Answer:

Let us consider this word on the following levels:
-  Its pagan connotations
-  Its use and meaning in Hebrew
-  Its use in Christianity and Judaism
-  Should we use it or not?

'Amen' was one of the main deities in Egyptian mythology, the worship of which  spread to Greece, Syria and surroundings.

According to 'The Concise Columbia Encyclopedia',  Columbia University Press.  Copyright © 1991 by Columbia University Press:

Amon (â´men, ä´-) or Ammon (à´men) or Amen (ä´mèn), ancient Egyptian deity. Originally the chief god of Thebes, Amon grew increasingly important in Egypt, and eventually, as Amon Ra, he was identified with RA as the supreme deity. He was also identified with the Greek ZEUS (the Roman JUPITER). (Ed.: Jupiter or 'Zues-Pater' - 'Zeus our father').

The Official Internet Site of The Egyptian Ministry of Tourism
has the following Web Pages with information about Amen, the primeval idol:
Amen (Amon) and Amen-Ra, King of the  Gods, and the Triad of Thebes
Amen worship
Amen of Thebes
Forms of Amen-Ra
Here are some excerpts from these informative pages.
"Amen was the personification of the hidden and  unknown creative power which was associated with the primeval abyss, gods in the creation of  the world, and all that is in it. The word or root amen, certainly means "what is hidden," "what  is not seen," "what cannot be seen," and the like, and this fact is proved by scores of examples  which may be collected from texts of all periods. In hymns to Amen we often read that he is  "hidden to his children, "and "hidden to gods and men" ... Now, not only is the god himself said  to be "hidden," but his name also is "hidden," and his form, or similitude, is said to be  "unknown;" these statements show that "hidden," when applied to Amen, the great god, has  reference to something more than the "sun which has disappeared below the horizon," and that it indicates the god who cannot be seen with the mortal eyes, and who is invisible, as well as inscrutable, to gods as well as men."

Amen, his wife, Mut, and their son, Khonsu, represented the Theban Triad, the sacred family of Thebes. Amen was the "King of the gods" during the period of the New Kingdom in Egypt 1550-1070 B.C.E. when Thebes was the capitol of Egypt.  (refer http://www.wsu.edu/~dee/EGYPT/NEW.HTM
http://www.civilisations.ca/membrs/civiliz/egypt/egcrga2e.html

It is during this period that the Israelites were slaves in Egypt, building the fortifications and lavish statues and temples of Egypt.  During their 400 years of slavery, they lost their patriarchal Yahwistic religion as they fell into Egyptian paganism.  Their epic exodus required a 40 year 'cleansing' period in the Wilderness,  before they could enter the 'Promised Land of Israel'.

If during this exodus they could build a golden calf idol,  would it be far-fetched to surmise that they also carried the blemishes of Amen-worship with them into the future - a seed which may not have been uprooted to this day?

Which brings us to our 2nd point of consideration:  The word 'amen' is popularly used in Hebrew liturgy and Jewish worship.

True, the root-letters  a-m-n hold the following connotations in modern Hebrew:
educate, train, true, trustworthy, confirm, confidence, faithfulness, treaty.

Thirdly, its use in modern day Judaism and Christianity:

The meaning for the word 'amen' is given as "so be it", "trustworthy"

Knowing the pagan idol worship connotations of this word,  it does raise concern when one hears those phrases which are so popularly used in Christian prayer:
"We ask this in Thy Name, Amen".
"We praise Thy Name, Amen."
"We ask this in the Name which is above every Name, Amen".
"Praise the Lord" - with the communal response: "Amen".
These above applications surely can pass for directly addressing someone named  'Amen'!  It should surely be conspicuous to the alert worshipper of the One True God of Israel!

Similar usage is also common in Jewish worship liturgy.

Should we use it in prayer and worship?

The position assumed in all the Restorative Truths proclaimed by BIBLE REVELATIONS, is to avoid extremism.  This position is also maintained in our study on the use of  'God or Elohim'  and the use of the various forms of The Sacred Name.

Like with all other considerations in the process of the Restoration of the Original True Hebraic Faith though,  the question remains:  "What does the Almighty expect from us?"  Our intentions may be pure, but why persist in clinging to habits and traditions which have spurious origins or connotations?  Do we really need this word to express our convictions and praises?

It also is curious,  that this almost mystical word, anciently referred to the "hidden god" - and it would surely not be far-fetched to surmise that perhaps Satan has managed to hide himself as the object of worship, to unsuspecting believer to this day?

Could this realisation and avoidance oof such spurious terms lead us further from the Truth or closer to it?

Is this not after all the purpose of true and pure worship,  that we become aware of the traits and methods of the Deceiver and refine and purify our worship as far as is humanly possible?  What are we defending by hedging against doubtful practices?  There are, after all,  'pure' words like "HalleluYAH", or where necessary, the Sacred Name itself,  which can replace this questionable praise word 'Amen',

Ex. 23:13:"...and make no mention of the name  of other gods, neither let it be heard out of your mouth."