It is possible to mistake legalism and licentiousness as being two polar extremes of errant Christianity with the Gospel life somewhere in the middle.
This is not correct.
Jared Wilson explains:
When I see people weary or hardened under the brutal weight of religious hyper-spirituality, I am saddened that they do not know the freedom of the gospel of grace. And when I see people indulging in the hedonistic excess of license, I am saddened that they do not know the freedom of the gospel of grace.
Legalism and license are separate categories. But they are in the same category of Departure from the Gospel. Neither cures the other, but the gospel cures both.
mgpcpastor's blog 
The gospel is the narrow road with the ditch of legalism on one side and the ditch of licentiousness on the other