One of the most frustrating things to deal with is people who understand that justification is by faith through grace and therefore believe there is no possible way that they are legalistic though they believe that they must follow laws in order to be sanctified. It's frustrating because the book of Galatians was clearly written specifically to deal with those who began in the Spirit by faith but were trying to 'be perfected' (hello, sanctification!) in the flesh. 'In the flesh' is clearly connected to 'under law' if you read on in chapter 3. So I was happy to find that Steve McVey addresses this very thing briefly in one of the 101 lies videos, Christian lies #30 "legalism is salvation by works".
If you are one of those who believe that salvation is from faith to works, I hope you are able to re-read Galatians keeping in mind that their problem was not beginning right but not continuing in faith. Don't worry! I'm not saying grace is a licence to sin! True sanctification will only happen if you believe God enough to totally abandon any hope in your obedience to the law and live by his Spirit. Do you think he will lead you into sin???????????