The truth is more straightforward.
When Christianity first came into existence, it was already culturally situated. It was Jewish. It was a story of the Jewish Messiah coming to the Jewish people to fulfill all the promises and prophecies of the Torah and Tanakh, with specific reference to the latter. It was articulated in Aramaic, and couched in Mideastern idioms and expressions. It did not appear as a sort of "blank" or cultureless thing, ready to sponge up Greek culture; it had its own identity, culturally speaking.
That was precisely the Pharisaic understanding of things.When God gave commands to the Hebrews he did not offer options. It was not to be rationalized. It could not be objected to on ethical or moral grounds nor any intellectual ground. Commands had to be obeyed or the consequences would be dealt with. When a command was disobeyed, starting from that fateful apple, sin resulted. Sin is a result of disobedience. I don't think there can be any doubt about this.
But you can see that Christ Himself took them sharply to task for their legalism -- whether it was their Sabbath prohibitions, their limited understanding of moral sins, their myopic view of God Himself, their trite understanding of history, or their imperious assumption of racial superiority. He took them on, on all these points.
For Jesus Christ, a command was never just a command. It was instead, a principle as well, a principle indicating that which is harmonious with the character of God Himself. And failure to understand or actualize a command could happen on terms much more broad than simply failing to follow the letter of it. We see this in his indicting of their view of enemies, of adultery, or of murder in the famous Sermon on the Mount, for example. Knowing HaShem was never about mere commandments, single axioms devoid of resonances and applications. It was always about total character and relationship.