8 Formerly, when you did not know God, you were slaves to those who by nature are not gods. 9 But now that you know God—or rather are known by God—how is it that you are turning back to those weak and miserable forces? Do you wish to be enslaved by them all over again? 10 You are observing special days and months and seasons and years! 11 I fear for you, that somehow I have wasted my efforts on you. (NIV)Paul's main argument comes to a close in this section. It also serves as a bridge to the next section where Paul makes requests of the Galatians. Here Paul addresses the Galatians directly and building off of a shared belief. Prior to becoming Christians, the Galatians were enslaved in their prior religions. The direction Paul goes next, though, is simply shocking. In reiterating his point from the prior section, he claims that if they observe Torah with the aim of becoming full members of God's people then they are actually going back to their pre-Christian state. They already were God's people because God's Spirit, the Spirit of the Son dwelt within them. God's Spirit was in them, hence they were known (i.e., loved) by God as his children. By observing Torah they would be placing themselves back into a state of slavery.
Paul continues this line of reasoning in verse 10. 'Special days, months, seasons, and years' is an allusion back to the creation story of Genesis 1 (specifically Gen. 1:14). If the Galatians start observing the Torah and its sabbaths and festivals they are putting themselves back into the old creation, rather than living in the new creation. Jesus work on the cross was decisive and the turning point in history. Their union with him was the turning point in their history. To intentionally rely on anything else other than the work of Christ puts one decisively outside of the people of God. Thus Paul argues that by observing Torah they will actually achieve the opposite of their aims. They will forfeit their standing. That state of affairs is also the opposite of what Paul wants to see. Paul has expended a lot of effort to ensure that the Gentiles get a seat at the table and are considered full members of the people of God (see chapters 1 and 2). He fears that all of that work may be for naught, at least in the case of the Galatians.