I would not consider Jesus to operating from a liberal Jewish perspective by today's understanding of liberal religious or political perspective. Jesus was a rebel in his own perspective. In some ways he demanded the compliance to the Law rejecting the pragmatic corrupt Jewish establishment that compromised with the Romans.
That all depends on which Jews, Jesus is in reference to.
Note Romans 9:6--" Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel"
Therefore they are not all Jews, which are of Israel.
So what's the difference between one Jew and another Jew, What is it that separates the two?
Note that Jesus denounce a certain sect of Jews, who came to him professing to be the children of Abraham's.
John 8:39--"They answered and said unto him, Abraham is our father, Jesus said to them, If you were Abraham's children, you would do the works of Abraham"
Notice Jesus said ( If you were) meaning those Jews are not the children of Abraham.
So who's children are they?
Jesus tells them in Verse 44, exactly who their father is
Verse 44--" You are of your father the devil, and the lusts of your father you will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it"
So who was the murderer in the beginning
( Cain) that's who, so Jesus telling those Jews their father is Cain, Seeing Cain committed the first murder.
Genesis 4:8--"And Cain talked with Abel his brother: and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him"
There you have it, Cain committed the first murder. Therefore those Jews, that Jesus was speaking to, are the children of Cain's and not Abraham's children.
In the old testament scriptures, the children of Cain's are called ( kenits) and those Jews which were masquerading as Jews of Israel, the children of Abraham's. Unto which Jesus called them out exposing them as the children of Cain's. (Kenits)
All a person needs to do, is follow the genealogy of Cain's which comes down as being called ( Kenits ) the seed ( children) of Cain's.