21 Tell me, you who desire to be under the law, do you not hear the law? 22 For it is written that Abraham had two sons: the one by a bondwoman, the other by a freewoman. 23 But he who was of the bondwoman was born according to the flesh, and he of the freewoman through promise, 24 which things are symbolic. For these are the two covenants: the one from Mount Sinai which gives birth to bondage, which is Hagar-- 25 for this Hagar is Mount Sinai in Arabia, and corresponds to Jerusalem which now is, and is in bondage with her children-- 26 but the Jerusalem above is free, which is the mother of us all. 27 For it is written: "Rejoice, O barren, You who do not bear! Break forth and shout, You who are not in labor! For the desolate has many more children Than she who has a husband." 28 Now we, brethren, as Isaac was, are children of promise. 29 But, as he who was born according to the flesh then persecuted him who was born according to the Spirit, even so it is now. 30 Nevertheless what does the Scripture say? "Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman." 31 So then, brethren, we are not children of the bondwoman but of the free. (Gal. 4)Those who follow worship practices there were inseparably linked to temple worship fall into this category of following after earthly Jerusalem (Note that even Paul recognized he needed to return to Jerusalem to participate in “the feast” and Pentecost; Acts 18:21; 20:16). Those who follow old covenant worship practices are the children of Hagar by this analogy.
Paul’s entire emphasis in Galatians is that members of Christ’s body, the true sons of Abraham, not put themselves into the position of denying the Lord by the chasing after the things of the Law. Those who wish to merely keep the convenient aspect of the law are under a curse. As Paul says, "Cursed is everyone who does not continue in all things which are written in the book of the law, to do them" (Gal. 3:10). Unless you can observe the "jots and tittles" then you are under a curse.
I have to correct your understanding of the law as it relates to the new covenant...at least for the benefit of any lurkers that may be hanging out.
There was a thread on Jesus's Teaching on God's Laws not too long ago. It answers most , if not all, of your erroneous assumptions.