The word Legalism predates Jesus by roughly 400 years. A man named Shang Yang, a Chinese Statesman, started the philosophy of rule by law. Fast forward roughly 400 years to the times of Jesus. HE never once taught or acted in a way that would infer His Father’s commands were legalistic. In fact, HE upheld the commands and taught those around Him to do the same.
“But it is easier for heaven and earth to pass away than for one dot of the Law to become void”
“Has not Moses given you the law? Yet none of you keeps the law”
“Whoever has my commandments and keeps them, he it is who loves me”
“For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished”
The theology behind the following of commands making one a Legalist would then convict Jesus of the same offense.