Central to classical theism is the conception of God as the sole ultimate reality, the Creator of all things apart from Himself. This doctrine receives its most significant challenge from Platonism, the view that there are uncreated abstract objects, such as numbers, sets, propositions, and so forth. According to Platonism there is a host of objects, indeed, infinities of infinities of beings, which are just as eternal, necessary, and uncreated as God.
William L. Craig (via philosophy-quotes)