Early on Satan wrote letters to his friends Gabriel and Michael from Earth. What fascinated him most is the religion of the Christian portion of the inhabitants. In one of his reports he writes:
These people cannot stand much church -- an hour and a quarter is the limit, and they draw the line at once a week. That is to say, Sunday. One day in seven; and even then they do not look forward to it with longing. And so -- consider what their heaven provides for them: "church" that lasts forever, and a Sabbath that has no end! They quickly weary of this brief hebdomadal Sabbath here, yet they long for that eternal one; they dream of it, they talk about it, they think they think they are going to enjoy it -- with all their simple hearts they think they think they are going to be happy in it!
It is because they do not think at all; they only think they think.