在阿奎那的神哲學體系中，形而上學與創世論互為表裡。阿奎那在他的形而上學中把存在理解為純粹活動、本質的現實化，而本質則是萬物是其所是的根據，從而突出了存在的現實性和本質的潛在性，以及存在對於本質的優先性。他也遵循了存在即善的原則，從分有的角度看待萬物的存在與善及其與上帝的存在關聯。基於此，阿奎那指出，作為世界的唯一的第一原則，上帝的本質就是他的純粹存在，創造作為上帝的本質體現和神聖活動，就是存在之給予。而世界萬物之受造，就是存在之分有，世界萬物既絕對地受造於上帝，又自有其分有之在，表現為存在論上的依存性和自在性。阿奎那站在存在論的高度深化了基督教「無中造有」的創世觀念，構建了一種新的經典範式。

In Aquinas' philosophical theology, the doctrine of creation was not only held on faith but can also be proved by a demonstration. According to Aquinas, to be is to be in act, essence is what it is to be a thing, and to be is to be good. Aquinas emphasized the reality of being, the potency of essence and the priority of being to essence. He also insisted that to be is to be good and that all things get their good and being by participation. Aquinas's doctrine of creation was corresponding with his metaphysics. God, as to its essence, is nothing but pure act. Creating, as God's divine action, is but to give being. And the creatures, as to their existence, were created by God. Although things come from God absolutely, they have their own being. Based on his ontology, Aquinas deepened the Christian doctrine of Creatio ex Nihilo and established a new classical paradigm.