In situations where Ritual prayer is not used, pray from your heart. A WM is in the East for a while, GATU is there forever.
When called upon for a blessing for the food I say something like: "We thank the Earth for our food, and the Great Architect for our time together - so mote it be". No one has ever complained.
Amen was a particular Egyptian god - that by some accounts was cast out by the other gods for wrong-doing. Thus he went into hiding but his priests put a spin on the situation saying that he was the hidden god.