What do we mean by the word 'God' ?

As a parish priest, first in England and now in Co. Clare, Ireland, whenever someone says to me ‘I don’t believe in God’ generally the first question I ask is “Define the God you don’t believe in’ and the second is ‘What do you mean by the word ‘believe’”?

Because all too often we use these words as if there is one agreed definition as to what they mean, but, in reality, we can all mean something quite different when we profess to believe or not believe in God.