Fulton J. Sheen,

“Very few people believe in the devil these days, which suits the devil very well. He is always helping to circulate the news of his own death. The essence of God is existence, and He defines Himself as: 'I am Who am.' The essence of the devil is the lie, and he defines himself as: 'I am who am not.' Satan has very little trouble with those who do not believe in him; they are already on his side.”