Perhaps you don’t know what Judaism is, since you are conflating it with the faith that Moses, the Prophets & the Messiah taught.
Judaism is what Paul excelled in:
Galatians 1:13-14
notice that Paul equates Judaism to “the traditions of my fathers”.
The Pharisees were practicers and promoters of JUDAISM, which is why they asked the Messiah this question:
Matthew 15:2
nowhere will you see any prophet or apostle teach or promote any form of Judaism.
Paul left/denounced Judaism to follow the faith of Messiah, Moses & the Prophets.
He was against Judaizers, who were trying to convert followers of the Messiah into Judaism. Judaism does not teach the correct way of being righteous before God, which is faith.
You have conflated... what Judaism was. With what it had degenerated into. It is like the Vatican claiming to be the first church. It was the first church for the gentiles. Today many still refer to it as "the church." But, its no longer what it used to be while it lasted being the church.
Martin Luther started what we today refer to as Lutheranism. What Martin Luther wanted to do was to have the church return to being once more the church it should be. Martin Luther was ironically being a good Catholic.
Words change their meaning over time. Same word, but with a different implication.
For example? Someone who is a part of the Marxist Black Lives Matter leadership can claim to be American. When in another country, when asked? They can say they are Americans. Far from it. But technically correct. In that sense? Judaism was still called Judaism when Jesus walked the earth...
Think about this.. Jesus operated (as prescribed by Judaism) into making himself a rabbi, and choosing who were to be his disciples. It was common pratice. Rabbis did that in his day. As per "Judaism."
Jesus and the prophets wanted a return to unadulterated Judaism.
Jesus even said about the Pharisees the following...
Then Jesus said to the crowds and to his disciples:“The teachers
of the law and the Pharisees sit in Moses’ seat. So you must be
careful to do everything they tell you. (the Law) But do not do
what they do, for they do not practice what they preach." Mat 23:1-3
The Pharisees were proclaiming Scripture from the Torah. Judaism! But, they would not live it themselves. That is why Jesus said to do as they tell you (quoting Scripture). For the Pharisees were continuing the practice of Judaism superficially having only an outward appearance of Judaism.
Jesus was telling the Jews to do as Moses said. But, not to follow the example the Pharisees lived themselves. Its like Obama, or Nancy Pelosi quoting from the US Constitution. We will hear what the Constitution says and we will acknowledge it. But the ones citing it? They turn around and begin distorting its intent.We do not follow them if we respect the Constitution.
In other words? Jesus was telling the Jews to stick with God's Constitution (the words of the Torah = true Judaism).. but, to ignore the ones proclaiming the Torah to them while distorting its intent in their own life style.
Judaism had become corrupt! It was still referred to as Judaism.
Let's see...
You car is what? Let's say, "a Ford." Does it stop being called a Ford if its been illegally and dangerously modified? No. Its still called a Ford..
"Officer! Its that Ford over there! That's the one you're looking for."
Phariseeism was dangerously modified Judaism.
Phariseeism
Such is Life.