What are miracles? I have written elsewhere about the problem of definitions. When we attempt to define something we find there are always exceptions. Here we are interested in those events in Scripture, such as Moses parting the Red Sea and Jesus walking on water or raising Lazarus from the dead, which are commonly recognised as miracles.
Such events are super-natural or extra-ordinary in the sense that they are not explicable in natural or ordinary terms. God causes everything in his creation but on such occasions he acts in a highly unusual manner. That is, a miracle occurs when God acts differently from his usual providential activity in his creation, displaying his power and control by intervening to do something which cannot be explained by the laws of science (because these simply describe God’s usual activity).
Benjamin Warfield said, ‘A miracle is an event in the external world produced by the immediate efficiency of God.’ (By ‘efficiency’ here he means God acts directly.) Similarly, Louis Berkhof wrote that a miracle is ‘not brought about by secondary causes that operate according to the laws of nature’.
This does not define miracles as simply events we don’t understand, with the implication that one day with advances in science we may be able to explain them. No. Such events remain ever beyond scientific explanation just because God has acted differently from how science describes his usual activity. He acts immediately, directly, without using his usual secondary causes.
Wayne Grudem defines a miracle as ‘a less common kind of God’s activity in which he arouses people’s awe and wonder and bears witness to himself’.