The Jews have been making changes to their laws from the time Moses first revealed the Ten Commandments at Sinai. Many of the changes occurred when the Jews returned from exile in Babylon and built the Second Temple. It was at the end of this period that the Rabbis found that the death penalty was too draconian a punishment for civilized peoples. They put in place so many restrictions on Capital Punishment that it effectively became abolished. From that time forward, no Jew was ever executed for blasphemy, adultery, working on the Sabbath, disobeying his parents or apostasy.
A thousand years later Jewish sages extended this idea further even to murder and so we have Miamondes writing: "It is better and more satisfactory to acquit a thousand guilty persons than to put a single innocent one to death."
Unfortunately for Muslims, Mohammed copied the punishments for various offenses from the Old Testament without the ameliorating effects of later Jewish Rabbis. And so there they have remained, savage and brutal, immutable and unchallenged for the past 1400 years.
If our Constitution were like the Shari'ah we could never change it nor add amendments. Slaves would still be slaves and women would not be allowed to vote. The reason? The Shari'ah is fully complete. The Prophet Mohammed (PBUH) conveyed the entirety of the Shari'ah from Allah and did not conceal even one part of it. This is one of the fundamental principles of Islam: the Shari'ah is complete and perfect, free from contradiction and inconsistency. Nothing can be added, nothing can be changed.
Anyone who questions, or wishes to change even one word of the Shari'ah is guilty of unbelief, or more specifically Kufr ul Istibdal 1, the punishment for which is death.
Hammurabi gave the world a set of laws called Hammurabi's Code, one of the first written codes of law in recorded history. These laws were written on a large stone monument standing over eight feet tall and put in a public place so that all could see it and is now in the Louvre Museum in Paris. It should be noted that it is hard to change a law written in stone.
Changing the law to be more humane is one of the great achievements of mankind. The Jews updated their view of the death penalty, just as in the US we changed our laws regarding slavery. What Lincoln did was not to deny the US constitution but to affirm its promise of liberty to all men. Sadly Muslims believe that changing one word of a primitive, savage law is blasphemy and a corruption. That is why Islam is antithetical to our way of life.
Muslims will sometimes defend the barbarity in the Quran by noting that the Old Testament contains similar barbarities. But that is like defending slavery today in many Muslim countries by pointing to Article 1, Section 2, Paragraph 3 of the United States Constitution which counted slaves as 3/5ths of a person.
Jews do not go around committing atrocities quoting passages from the Old Testament. No American goes out buying a slave by quoting obsolete articles in our Constitution.
But the Shari'ah has not changed since Mohammed last pitched his tent on the sands of Arabia.