Thank you for your reply. 
I agree that the woman is the church and that Satan wants to destroy her/us. But, how does the earth help her? The earth and sea are symbolic of unbelievers. How does their swallowing the deception help the woman?
I do not know if its a deception or a vicious persecution that is being talked about here. But it seems to me from just seeing how evil and the world works in practice that very often evil people and forces are their own worst enemies and that the efficiency of their purpose is undermined by that. The Nazis or Communists being perfect examples.
So what's the devils purpose - obvious one - he wants to destroy the church.
How could the earth i.e. the devils realm get in the way of that. Well the passage does not actually say does it, but as I said in my previous reply there are various ways in which the devil might have been tripping over his own feet on this one.
For instance a self interested worldly man might interpret a full out assault on his Christian neighbours as an assault on his own property or life and get in the way of that assault and even oppose it for instance as did many godless Romans who defended Christians against the barbarian invasions of the 4th century. The fury of the barbarians was very often expended against these men and the Christians ignored as a result, to survive and prosper into the new order of the dark ages.
Another way the devil can trip over his own feet is in the ways in which the culture he helped to build, as a way of bleeding away faith and crippling Christians, gets in the way of his own efficient execution of his purpose. So for example laws protecting freedom of speech which he used to foster a culture of lies and to encourage false relgions might be used to defend Christians against persecution.
A third way might be because he ends up targeting a third group of people who actually already belong to him. He ends up destroying them when he really wanted to destroy the church. These false Jews-Christians could be any group of people that the world throws in the way of his purpose at the time.
"For who can understand the mysteries of Christ"
