In William Shakespeare's tragic play Macbeth, Macbeth is unable to say the word "Amen" after murdering Duncan. Macbeth is "caught" by Duncan's servants while in the act of murdering the king.
One cried "God bless us!" and "Amen" the other;
As they had seen me with these hangman's hands.
List'ning their fear, I could not say "Amen,"
When they did say "God bless us!" (II, ii, 24-27)
First, one must understand what Amen means. Amen is used at the closing of prayer, or it means "So be it" (taken from Hebrew). If one were to examine both, one would understand why Macbeth is unable to say Amen.
As seen in the text, Macbeth says the word "Amen" four different times in the scene. Therefore, he is able to say the word Amen. The symbolic nature of the word arises though when one examines it using its true purpose: to end a prayer or to ask for something to be ("So be it"). Therefore, Macbeth is not able to ask for anything given his committing of a sin. His guilt lies so heavy on him, initially, that the word simply becomes lodged in his throat.
Therefore, Macbeth is not worthy of prayer and his guilt is far to overwhelming at this point. Macbeth's physical reaction to the murder he has just committed (the sticking of the word in his throat) shows both his guilt and remorse.
"Amen" is a well-known word with religious significance. It has been around for thousands of years, and is used to show agreement and confirmation of something or some point which is why it appears at the end of so many prayers. Congregations confirm what a priest or preacher has just said or what they have said in unison, verifying the truth of what has been said, its grounds and their agreement. In a modern context, outside of its religious context, those in agreement with each other may say something like "Amen to that" when they want to express their consensus. In Macbeth, Macbeth is a respected and loyal subject of Duncan. At first, he is even shocked at his own callousness and intent. Having decided not to proceed with his plan to murder Duncan, he allows himself to be persuaded by Lady Macbeth that he should go ahead with it and Lady Macbeth convinces him that it will reveal that he is "so much more the man" (I.vii.51).
In Act II, scene ii, Macbeth kills Duncan and relates to Lady Macbeth the disturbing comments of Duncan's aides, whom they intend to blame for Duncan's death. Macbeth expects them to remain asleep but when they see his bloody "hangman's hands" (28) and one cries, "God Bless us" (27), Macbeth is so conflicted because he knows that God will not spare them as Macbeth will kill them to save himself. Therefore, for Macbeth to say "Amen" at that point would be to lie in the face of God because his wish would be for God to save only him. He does not want them spared for obvious reasons, as they will be able to reveal his guilt. So he cannot agree with them by uttering the common "Amen."
This also reveals the extent of his superstition. If he agrees with them, perhaps they will be spared by some miraculous intervention, and that will certainly be catastrophic for him. The fact that "Amen...stuck in my throat" (32), and that he later reflects on this, foreshadows the disastrous chain of events that will follow. He admits that "I had the most need of blessing," and now, having been unable to agree with their prayer, he may have doomed himself.