In quite a few translations is the text differently rendered, but this is the question that Paul asked the Galatians:
Where then is your happiness?
A few years earlier, Paul had, in the regions of Galatia, preached the evangel of grace (1:6; 4:13). They had received him as a messenger of God, as Christ Jesus Himself (4:14). But a change had come about, due to some preachers having come in, who Judaized them, i.e. they made them to accept Jewish customs (Gal.2:14). They promoted living under the law (4:21), as for instance, imposing on them circumcision (6:12) and keeping track of days, months, seasons and years (4:10). The apostle is exceptionally sharp to those with such a message of perverting the Evangel of Christ (1:7,8). Bewildered, he wondered, Who has bewitched you (3:1)? The Galatians had received the Spirit without "works of law", purely by the hearing of faith, i.e. a word of promise (3:2), the same as ever Abraham believed God's promise (3:6-9), centuries before the law was given (3:17). How foolish, therefore, in Paul's eyes, that these Galatians, who first began enthusiastically in-Spirit, now in-flesh wanted to complete themselves (4:3).
It is against this background that Paul asks the Galatians to look into the mirror: Where then is your happiness? They were ever so happy with the Evangel. Very logical, because Evangel means: Good News. What else would a really good message do than make them joyful and happy? The good message that they had heard spoke of grace. Grace versus works, because "… otherwise grace is no more grace" (Rom.11:6). In the Evangel of grace, the focus is purely and only on what GOD has done, on what GOD is doing and on what GOD will do, as yet. Such a word of grace makes us happy, because the accomplishments of man do not play any role. Are they there, then it does not make us more worthy, are there none, then we are no less. Only such a message constitutes a solid foundation for happiness. Through the preaching of law, this happiness had disappeared by the Galatians. And so it will go, always. Grace makes happy, while law frustrates. Law points out and establishes man's failures, while grace lifts our head on high, to glory in God. How very important, therefore, to remain with the evangel of GOD'S GRACE, and not to deviate from it, even one millimeter.
Translation: Peter Feddema