well, yes, this is certainly true of the gospel of john. john was never directed at jewish people, but to direct people AWAY from it.
the textual indications are of course that jesus's preaching was largely directed at jews, and not to radically change the religion itself -- just to redirect the hearts of the people.
"You have heard that it was said, 'An eye for and eye, and a tooth for a tooth.' But I say to you, do not resist him who is evil; but whoever slaps you on your right cheek, turn to him the other also."
Lev. 24:19-20 "'And if a man injures his neighbor, just as he has done, so it shall be done to him: fracture for fracture, eye for eye, tooth for tooth; ..."
So, exactly how do I obey Jesus, without violating Moses' law?
this mosaic law, like the babylonian precept it was stolen from, is designated limits on proper punishment and repunative measures. the idea was to establish a principle of fairness. often, in terms of goods (verse 21) the principle is repayment or replacement as punishment, but for things such as eyes and teeth, which could not be replaced, the same was still required of the offender. that is, should the original victim require it. but that was the maximum that could required. just one life, for one life. one eye for one eye, etc.
what jesus was trying to do was point out that revenge, though legally allowable in this instance, was not a good thing, and it should not be motive of a person. it was not exactly an attempt to change the law of moses (presuming this is an actual mosaic law and not picked up later in babylon), but redirect the people under it. sort of the difference between laws and personal principles.
i think, i'll have to check, that every verse following the proclamation of not changing the law, is this way. in that case, the verse serves as a sort of disclaimer.
but anyhow, as for jesus's real message, should he have really existed, we may never know. all we have of him is bias propaganda literature, all with their own political intents.