In this epistle to the Galatians, not only do we have a contrast between the old Israel and the new, we also have a contrast between the old world and the new, between the old heavens and old earth, and the new heavens and the new earth.
He is talking about the old world, constituted of Jew and Gentile. But the old order of things has passed away. That includes the witness God had established for Himself in that old order, which was the old Israel. In the old order, the Gentiles used to be in bondage to the elementals, and the Jews were in the bondage of having to learn her lessons. In that old order, the Jews were the elect people of God, but now that Gentiles have been included in the household of faith in the new world, for those Gentiles to go back to the godly old order is still going back to the old order.
The Gentile knowledge of God is the result of the grace of God. But if we speak this way too readily we can come to forget that it is in fact grace. So we remind ourselves that the Gentiles were known by God first, and as a result they came to know Him.
But what were these weak and beggarly elements? This idea of the stoichea was common in the ancient world. Plato, Aristotle and the Stoics all shared this view of the cosmos as made up of earth, air, water and fire. Aristotle added the possible fifth element of ether. Paul says that these things are by nature not gods. He is implying, further, that for residents of the new order to return to the Mosaic code, which was by nature from God, was tantamount to returning to the pagan idolatry that was pervasive in the ancient world also. Note also that the stoichea are fundamental to the philosophy of the ancients. Philosophy and cosmology are not separable. There is one use of the word to refer to the basic principles of Christian teaching (Heb. 5:12). Here in Galatians the word refers to the rudiments of the old world. In Colossians (2:8,20), it refers to the rudiments of the world, in opposition to Christ, of which pagan philosophy was a natural expression. In Christ, we are dead to the stoichea in this sense. In 2 Pet. 3:10-12 stoichea refers to that old heaven and earth that was to be replaced by the new heavens and new earth. The parallel between this passage and Jude (17-19) shows us that this great transition occurred in the first century.
Now remember the temptation the Galatians were facing—they were being enticed to accept circumcision, along with the rest of the Mosaic requirements. This would involve the ancient Israelite calendar, with all its anticipation of Christ, as though He had not come. Such cyclic observance of times (as a spiritual duty) is infantilism. Does this same temptation occur for those who follow the Christian calendar year? Yes, it most certainly can, depending on why the seasons are observed, and how they are observed. It can also happen to those who refuse to define their year in terms of Christ, and find themselves observing Labor Day and Memorial Day instead.
Paul is assuming that God has really intervened in the lives of the Galatians. He assumes that they are known of God. At the same time, he fears that his labor with him may have been in vain. Nothing is more apparent than the fact that Paul is dealing with the Galatians in covenantal terms. He is not saying that he, Paul, has seen the secret decree concerning them. But he does know their place in the covenant. Because he has not seen the decree, he fears that they might fall. They are showing clear signs of their readiness to fall. But because he knows their standing in Christ, he speaks of them as known by God in the covenant. He does not treat apostasy and perseverance as an abstract math problem.