[W]e must try to teach something about the difference between thinking and imagining. It is, of course, a historical error to suppose that all, or even most, early Christians believed in the sky-palace in the same sense in which we believe in the solar system. Anthropomorphism was condemned by the Church as soon as the question was explicitly before her. But some early Christians may have done this; and probably thousands never thought of their faith without anthropomorphic imagery. That is why we must distinguish the core of belief from the attendant imagining.
When I think of London I always see a picture of Euston Station. But I do not believe that London is Euston Station. That is a simple case, because there the thinker knows the imagery to be false. Now let us take a more complex one. I once heard a lady tell her daughter that if you ate too many aspirin tablets you would die. ‘But why?’ asked the child. ‘If you squash them you don’t find any horrid red things inside them.’ Obviously, when this child thought of poison she not only had an attendant image of ‘horrid red things’, but she actually believed that poison was red. And this is an error. But how far does it invalidate her thinking about poison? She learned that an overdose of aspirin would kill you; her belief was true. She knew, within limits, which of the substances in her mother’s house were poisonous. If I, staying in the house, had raised a glass of what looked like water to my lips, and the child had said, ‘Don’t drink that. Mummie says it’s poisonous,’ I should have been foolish to disregard the warning on the ground that ‘This child has an archaic and mythological idea of poison as horrid red things.’
There is thus a distinction not only between thought and imagination in general, but even between thought and those images which the thinker (falsely) believes to be true. When the child learned later that poison is not always red, she would not have felt that anything essential in her beliefs about poison had been altered. She would still know, as she had always known, that poison is what kills you if you swallow it. That is the essence of poison. The erroneous beliefs about colour drop away without affecting it.
In the same way an early peasant Christian might have thought that Christ’s sitting at the right hand of the Father really implied two chairs of state, in a certain spatial relation, inside a sky-palace. But if the same man afterwards received a philosophical education and discovered that God has no body, parts, or passions, and therefore neither a right hand nor a palace, he would not have felt that the essentials of his belief had been altered. What had mattered to him, even in the days of his simplicity, had not been supposed details about celestial furniture. It had been the assurance that the once crucified Master was now the supreme Agent of the unimaginable Power on whom the whole universe depends. And he would recognise that in this he had never been deceived.
C.S. Lewis, “Horrid Red Things,” God in the Dock (Eerdmans: 1970) 69-70.