What are the elemental spirits? If you follow St. Paul’s argument, the elemental spirits “enslaved” both the Jews under the Law and the Gentile Galatians under paganism.
St. Paul, following a line of Jewish interpretation, taught that the Law was not given directly by God but through the mediation of angels. (cf. Gal 3:19-20) Moreover, St. Paul believes that the idols of the Gentiles are representations of demons – fallen angels in this case.
Follow his line of thought in Gal 4:8-9:
Formerly, when you did not know God, you were in bondage to beings that by nature are no gods; but now that you have come to know God, or rather to be known by God, how can you turn back again to the weak and beggarly elemental spirits, whose slaves you want to be once more?
In other words the Gentile Galatians were formerly serving “beings that by nature are no gods,” that is to say demonic idols. Now they want to “turn back again to the weak and beggarly elemental spirits” by becoming Judaizers and submitting to the Law.
Their reversion to Judaism is for Paul a “turning back again” to the elemental spirits. I find this fascinating and I don’t know quite how to handle it. I can see how Marcion had a hey-day with this epistle and how he could use the language here to teach that the God of the Mosaic Law was actually a corrupt demiurge or “elemental spirit.”
Perhaps the best way to understand this is to read it in light of Hebrews chapter 1 where the author, like Paul (perhaps it really was written by Paul?!), explains that Christ is far superior to angels. The Gospel of Christ is revealed through the incarnation of Christ. We come to “know God, or rather to be known by God.” (Gal 4:8-9) The Law was given in the midst of thunder, clouds, smoke, etc. and apparently through angelic spirits. Even so it was given through a human man, Moses, who was not God.
When a person comes to Christ, his knowledge of God is directly through Christ. He can say “Abba” not through angels, elements, or men, but directly to God as a son to a father (Gal 4:6). It is not a mediated faith through angels or through men. For Paul, any attempt to know God in a way other than through faith in Christ is “slavery to the elemental spirits,” whether they be Jewish or pagan. The “fullness of time” has come for both Jews and Gentiles to receive the “adoption as sons” that Paul speaks about in the same chapter of Galatians, i.e. chapter 4.