Who are the two groups being addressed?
Galatians 6:4
"Each one should test their own actions. Then they can take pride in themselves alone, without comparing themselves to someone else,"
Outward religious appearance (like the Pharisees) of unbelievers.
Galatians 6:10
"Therefore, as we have opportunity, let us do good to all people, especially to those who belong to the family of believers"
Galatians 6:12-13
"Those who want to impress people by means of the flesh are trying to compel you to be circumcised. The only reason they do this is to avoid being persecuted for the cross of Christ.Not even those who are circumcised keep the law, yet they want you to be circumcised ."
Outward religious appearance (like the Pharisees) of unbelievers.
Unbelievers and believers are being addressed.
Galatians 6:1
"Brothers and sisters, if someone is caught in a sin, you who live by the Spirit should restore that person gently. But watch yourselves, or you also may be tempted."
So the sin here is keeping Torah?
Galatians 5:24
"Those who belong to Christ Jesus have crucified the flesh with its passions and desires."
Is this a passion and desire to keep Torah?
Did someone suggest keeping the law was sin? What does that have to do with the commandments of Jesus?
Since the letter is addressed to the churches of Galatia and the topic is the law, why do you think it addresses unbelievers who aren't part of the group?
Why do you ask? Didn't you read verses 1-23?
19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,
20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,
21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance: against such there is no law.