In Galatians 6:12, Paul speaks of the legalists as those “who would force you to be circumcised, and only in order that they may not be persecuted for the cross of Christ” (ESV). This describes many of the events that happen in church today.
The legalists were not so worried about the actual spiritual condition of the uncircumcised. Their concern was not that the uncircumcised could not be saved. They were worried about what their own people would think if they tolerated the gentiles remaining uncircumcised. But, according to Paul freedom from circumcision (and the rest of the law) was a fruit of the cross of Christ. This means they feared being persecuted by their own people for allowing gentiles to rest in the cross alone. In other words, their fear was that they themselves would look bad if these others were not brought into conformity.
There is an interesting dynamic that can be lost if we just stop here. Notice they were willing to force the conformity of others to prevent their own persecution. Their actions, like so much in church today, was spawned by selfishness.
Legalism and license are different sides of the same selfish coin.