If we assume that, at least for believers, such statements of religious fact are meaningful, we are faced with the need to consider the ways in which they may be said to differ from, for example, statements of scientific or technical fact. There is a good deal of what might be termed 'religious vocabulary' in our language, much of it also used in a variety of mundane contexts. This is necessitated by the fact that, in order to state that there is a God and to make other religious claims, theists use words in general use such as personal, creator, free and good, terms which we first learn to use from seeing them applied to everyday objects, states and feelings. Technical terms, such as omnipotent, for example, are also defined ultimately in terms of the standard usages of other everyday words. St. Thomas Aquinas, who put forward in Part I of his Summa Theologiae what is known as the doctrine of analogical predication, a difficult-sounding concept but one that can easily be explained by reference to simple examples.
Man is good.
Dog is good. It is clear that 'goodness' in a dog would be defined in terms of the qualities which serve to make a particular dog, a guide dog, for instance, a good example of its kind. The example works both from human beings 'down' to other creatures and 'up' to God, because God's 'goodness' is as different from ours as is the guide dog's. We cannot hope fully to understand the goodness of God, any more than we can fully understand that of a dog, but we can recognize the correspondence between them in terms of what they refer to and the ways in which statements about them require language to be used. In Aquinas's argument, therefore, language, in religious contexts, is used analogically.