Jews believe that there is an Original Being, and from the reality of that Being all things exist. Jews believe that this Being created the world with purpose, and provided the Jewish people with instructions through Moses.1

How the Beliefs of Judaism Began

The Jewish People are the children of Abraham. So to understand Judaism, we must start with the story of this great man, perhaps the most important individual in the history of the world, and the founder of Judaism.2

Abraham was a young child in one of the first great cities of civilization, Ur, in ancient Mesopotamia, about 4,000 years ago. His family and all the people around him worshipped the stars, the sun and the moon, as well as idols of stone, metal and wood. They worshipped images of their king and treated him as a god. Young Abraham also worshipped innocently along with them.

But already at a young age, Abraham grew skeptical of all these deities. He saw that the wind, the rain, the sun and the moon worked together in wondrous harmony. There seemed to be order among the stars in the night sky, as there was among the plants and animals on earth. Observing the world around him and the events of his lifetime, Abraham came to realize that there is really only one G‑d—a single force behind all that occurs, a single reality behind all that exists.

He asked himself, "How have people abandoned the one G‑d of heaven and earth to worship idols of stone?"

How Ancient Are the Beliefs of Judaism?

Many years before Abraham’s time, all people had known of the one G‑d. But they saw other great powers in the heavens. They felt that if G‑d had given these beings such power, they too should be honored. They did not deny the supremacy of G‑d. They thought it was His will that they worship these other powers.

Among these ancient ones were wise people who determined that this one, lofty G‑d is beyond all things that appear, change and fade away with time. Certainly, they thought, such a supreme and perfect G‑d is not concerned with the petty activities of human beings who are trapped in bodies of flesh and blood. They considered the everyday concerns of human beings the domain of lower powers, who were accessible and would respond to their worship.

Gradually, false prophets arose who told the people that certain angels or stars had spoken to them and declared that they should be worshipped in certain ways. The prophets built temples and fashioned idols representing these powers. They taught the people that if they worshipped a certain idol and performed a certain ritual they would be fruitful, successful and avoid punishment.

Originally, the wise people knew the truth about these powers, but eventually they too became trapped in falsehoods. Eventually, the one G‑d was almost entirely forgotten. The common people knew only the wood and stone to which they had bowed and offered sacrifices from their youth, as well as the men of power who demanded that they too be worshipped. Only a very small elite, to whom few cared to listen, retained the truth.

Read: The History of Monotheism

Abraham, Judaism's Great Iconoclast

But Abraham saw through all this. He realized that if G‑d is truly one, then there is no difference for Him between heaven and earth, great and small. And for G‑d to sustain such a magnificent, harmonious world, it must be that He is there in every event, and that every life is His concern. It is only that human beings are granted the free choice to stay in harmony with G‑d, through justice and compassion, or to stray down paths of darkness, corruption, violence and evil.

Abraham realized that it was the worship of idols that was concealing the truth. With no single G‑d to answer to, people had fallen to the depths of immorality, sacrificing their own children, justifying thievery, rape and murder.

So Abraham smashed the idols in his father’s house. He began to preach to people that they should worship only the one G‑d of heaven and earth who is found everywhere and is accessible to all. He taught that this one G‑d has compassion for all His creatures and demands honesty and justice from all. Abraham’s teachings spread rapidly, until much of the world was convinced.

Once Abraham had discovered these truths on his own, G‑d revealed Himself to him and assigned him the mission of spreading this knowledge. G‑d promised Abraham that he would be the father of many peoples.

How Abraham’s Beliefs Became Jewish Beliefs

Abraham passed the torch on to his son Isaac, who passed it on to his son Jacob. Jacob taught his 12 sons. But Jacob and his sons descended to Egypt, and their children became enslaved there. In Egypt, all that Abraham had planted withered away, and the flame he had lit was almost extinguished.

But out of His love for Abraham, and due to the promise He had made to him, G‑d sent Moses to redeem the people from Egypt. Moses was the greatest of all prophets. He brought the people to Sinai, where they heard the voice of G‑d directly, commanding them not to have any idols or worship any power other than the one Creator of heaven and earth. Because there is no power or force in all the universe other than Him.

Moses reminded the people that they had not seen any image when they heard G‑d at Mount Sinai. He taught them to recite twice a day: “Hear O Israel, G‑d is our G‑d, G‑d is one.”

This declaration is known as the Shema. Learn more about the Shema here.

What Do Jews Mean When They Say that G‑d is One?

When we say that “G‑d is one,” we don’t just mean that there is only one G‑d. We also mean that He has no parts, no body, no form, and cannot be grasped or defined in any way.

Nothing exists outside of His oneness. As Moses said to the people, "Know as clear as day that G‑d is the only power. In the heavens above and on the earth below, there is nothing else."

Not only is there no other G‑d—there is nothing else. Because the true reality of all we see is nothing more than G‑d's desire that it exist. Within each thing breathes that desire of G‑d, and without it nothing can be.

And yet, if all we see around us would suddenly disappear, G‑d would remain, unchanged.

G‑d is the only true reality, because His existence is not contingent on the existence of anything. And yet His will is invested in all things and sustains them at all times.

That is what we mean when we say that G‑d is one: He is everywhere, within everything. He is the oneness that encompasses all things. And yet, He transcends them all.

For more on the Jewish idea of monotheism, see the first chapter of Maimonides’ classic Book of Knowledge. Another great classic is The Portal of Unity and Faith, by Rabbi Schneur Zalman of Liadi. For a contemporary presentation of the same ideas, see our article, What Is G‑d?