While doing research for my (never ending) thesis on Romans 8.18-25 I’ve come across three basic interpretations of ἡ κτίσις:

(1) By far the most common is that it is the created order. The only other time Paul writes on ἡ κτίσις  is in 1.20-25 where “the creature/creation” (τῇ κτίσει) was honored rather than the Creator (τὸν κτίσαντα). In v. 23 Paul lists the basic categories of the created order that humanity was to oversee according to Gen 1.20-27 (καὶ πετεινῶν καὶ τετραπόδων καὶ ἑρπετῶν). It is most apparent that Paul has the Adam and Eve narrative in mind where they obeyed the serpent (creation) rather than obeying God (Creator). So when we read about creation waiting for its freedom from “its slavery to corruption” it makes logical sense to assume that Paul is speaking of Gen 3.17-19 where creation was subjected to decay because of human sin.

(2) Some have suggested that it is the human body since this passage is about the resurrection. I don’t find this necessary. There is more than enough room for Paul to talk about both the resurrection of humans and the renewal of creation, especially since the Book of Genesis and much of the rest of the Hebrew Scriptures connect the adam with the adamah or the human with the earth.

(3) One exegete, Susan Eastman, proposes that this is unbelieving humanity and that this passage teaches some sort of universalism in “Whose Apocalypse? The Identity of the Sons of God in Romans 8:19″. Of course, she is hard pressed to argue that the sons and children of God are different before v. 18 than they those mentioned after v. 18. Also, she has to argue this while for the most part ignoring the Genesis-Motifs that I mentioned.

I’ve concluded that the most probable interpretation, by far, is the more traditional one; namely, this is about the created order.