The three major western religions are extensions of the Old Testament. The Old Testament lays out the moral law for all of them, but each religion has its own way of trying to encourage people to follow the law. Christianity does this based on faith. If Christians have faith in Christ, then they try to follow his example which includes the morality of the Old Testament. Islam is based on submission. The idea is that all Muslims must submit to God's authority and it is this submission to authority that forces Muslims to follow the laws. And lastly, Judaism is based on observance which means following rules.
Judaism is basically obedience training. The rabbis make up all kinds of nonsensical rules and then require Jews to obey these rules. For example, the separation of meat and milk has absolutely no basis in the Old Testament. It is only part of Judaism as a form of obedience training. Jews do not have to be submissive (like Islam), nor do they have to have faith and believe (like Christianity). Jews only have to follow the rules. By constantly following rules, Jews learn to be obedient and this is how they are taught to follow the laws of the Old Testament.
You may wonder why no religion is based on following the Old Testament based on morality or thought. The answer is because people are too immoral and stupid for this to work. Karaite Judaism is an attempt to strictly follow the Old Testament directly, and Karaite Judaism simply lost out to Rabbinic Judaism because Rabbinic Judaism is more effective for most people.
I can picture Moses sitting alone on Mount Sinai thinking "how am I going to get these primitive slaves to behave?". If he were to to tell these people, "look, these are the rules that make a society successful, so follow them", he would have been ignored. Slaves only respect authority and power. So Moses invented a super-god, all-powerful with exclusive authority, who he claimed gave him the rules and will enforce them. This concept has worked throughout history because mankind has become increasingly slave-like over time. In a tribe, a man can speak his mind. But in a larger unit, there is always a central authority that doesn't appreciate independent thought. So this religion, designed by Moses for slaves, has become applicable to mankind in general.
The rabbis in Rabbinic Judaism seem to understand this. They have claimed the authority of God and use it to enforce whatever rules they make up. They invented "The Oral Torah" as a way to justify anything they say. The Oral Torah is nothing more than whatever the rabbis say, and this automatically gets considered to be part of the word of God. What the rabbis understand is that logic, reason, and truth are irrelevant to human behavior. Only authority matters. So the rabbis use authority to promote morality and they don't waste their time on irrelevant issues like logic and truth.