Amen

I just looked up the two pronunciations in English (British, Canadian, American, whatever) of the word Amen. I learnt it is because something that happened in 15th century England called the Great Vowel Shift. 

In Middle English (ME) "a" is pronounced as the "a" in "father." Early modern English (EME) pronounces the long "a" as in "gate."

ME pronounces the long "e" as the long "a" in "gate." EME pronounces the long "e" as the "e" in "tweet."

ME pronounces the long "i" as the "e" in "tweet." EME pronounces the long "i" as the "i" in "light."

ME pronounces the long "o" as the "o" in "tool." EME pronounces the long "o" as the "o" in "goal."

I try to remember to pronounce the word with a long a, because this is how it was pronounced in England in the years before the Reformation and for centuries after by Catholics, until Italian priests in the 19th century introduced the Italian pronunciation of Latin into the Mass. 

But it really doesn't matter. 

As Arthur John Balfour said, nothing matters very much and most things don't matter at all.

Patrick Benson tells me that 

"Many traditional Catholics following the old recusant pronunciation will say Amen (AY-men) and if the prayer is in Latin will use the Latin pronunciation AH-men. [Cardinal Heenan] the Archbishop of Westminster in the 1960s, encouraged Catholics to say Ah-men as it was the standard protestant English way and so they would be ecumenical sweeties and NICE! The traditionalists reacted by ensuring that they always said Ay-men. But then what about the evangelical, often, southern states Americans who say Ay-men ----was this the standard 17th cent. English pronunciation taken by them in The Mayflower?"