How Do We Know God is One?

How Do We Know God is One?

A Philosophical & Theological Perspective

– The oneness of God, in Arabic tawhid, is a central theme in the Qur’an and a message of all of the Prophets, the Qur’an eloquently describes the nature of God and His oneness in the 112th chapter, “Say: He is God, the One. God the Eternal. He begot no one nor was He begotten. No one is comparable to him.”

The concept of oneness in Islam is not limited to God’s singularity and uniqueness. It involves the way human beings should worship God, how they should understand His lordship, and how they should understand God’s names and attributes.

If God does exist what reasons do we have to believe He is one? There are many ways to answer the question referring to God’s singularity and uniqueness, thereby providing a positive case for the oneness of God range from theological to philosophical arguments.

Argument 1: Occam’s Razor

The Qur’an rhetorically asks the question “Did the universe come out of nothing?” Due to the metaphysical and undeniable logic, whatever begins to exist has a cause, and since the universe began to exist, therefore it must have a cause. Infinite regress of causes is impossible. It doesn’t make sense in the real world.

Ockham’s Razor is a philosophical principle attributed to the 14th century logician and Franciscan friar William of Ockham. This principle enjoins “Pluralitas non est ponenda sine necessitate”, in English “Plurality should not be posited without necessity.” In other words the simplest and most comprehensive explanation is the best explanation. A powerful being creating the whole universe is a far more coherent and simple explanation than a plurality of causes.

Argument 2: Logical Argument

Logic necessitates that if there were more than one God who created the universe it would be in chaos and there would not be the level of order we find in the cosmos.

However you may point out that your car was made by more than one creator, one person fitted the wheels, and someone else installed the engine and another person the computer system. So from this example there can be more than one creator with the created thing still able to exhibit order and stability.
God by definition is the being that has an unlimited imposing will. If there were two or more Gods that would mean that they would have a competition of wills and that would result in chaos and disorder. You may argue that they can agree to have the same will or each have their own domain, but that would mean that their wills are now limited and passive, which would mean they are not Gods anymore by definition!

Argument 3: Conceptual Differentiation

What makes us appreciate difference and duality? How do we differentiate between two people walking in the street? The answer lies in what is called conceptual differentiation. These concepts include space, distance, form, and physical features. In absence of these concepts we can’t perceive the two objects or any objects at all.
The cause of the universe must be outside the universe. If the cause was part of the universe it would mean that the universe created itself. This is absurd as it would necessitate the universe to exist and not exist at the same time!
If there were no cause for the universe then that would mean the universe, in the words of Bertrand Russell, “Is just there and that’s all”. In other words it would mean the universe is infinite, however this cannot be the case, as mentioned above the universe began to exist. Therefore a single independent cause is rationally necessary to explain the fact that the universe began to exist and that a plurality of causes cannot be perceived due to the absence of conceptual differentiators.

Argument 4: Uniqueness

The cause of the universe must be unique, as the Qur’an says “There is nothing like Him”.
If the cause of the universe was not unique that would mean there are some similarities between the cause of the universe and the universe itself. Why can’t the cause of the universe resemble the universe? The answer is straight forward; this cause must be immaterial because it created the sum of all material – which is the universe itself – and another principle that supports this is the 1st law of thermodynamics, it states “Energy cannot be created or destroyed”, simply put energy (in other words matter) cannot create itself.
The cause of the universe must be immaterial and therefore unique. How does this relate to the oneness of God? Well if there were more than one cause for the universe that would mean they are not unique anymore.

Argument 5: Revelation

How do you know God has announced himself to mankind and in what form is this revelation?There are only two possible ways to find out: externally and internally.

1. Internally

Finding out about God internally is implausible and would lead to fallacies because human beings are different. They have, what Psychologists call, “individual differences”, these individual differences include DNA, experiences, social context, intellectual and emotional capacities, gender differences, amongst many more.
These differences play a role in your ability to internalise via introspection or intuition, therefore the results of introspection or relying on your intuition will differ. From a historical point of view, since the ancient world 6000 BCE, there are records of approximately 3,700 different names and concepts for God!

2. Externally

It is obvious that the human being is not eternal, unique and powerful, therefore the human being could not conceptualise who God is. God would have to tell you via external revelation.
From an Islamic perspective this external communication is the Qur’an as it is the only text to claim to have come from God that fits the criteria for a divine text, these criteria include,

  • Consistence with the rational and intuitive conclusion on God

For example if a book says God is an Elephant with 40 arms you could safely assume that this book is not from God, as God must be external to the universe.

  • Internally and externally consistence

If the book says that the universe is only 6,000 years old then that would be an external inconsistency as reality as we know it s that the universe is older the 6,000 years.

  • It must have signposts to transcendence

It must have evidence to show that it is from God.  In the case of the Qur’an, supernatural explanations are the best explanation. Some of these signposts include:

A.The linguistic and literary inimitability

B.There are historical accounts that could not have been known by man at the time of revelation

C.There are some descriptions of natural phenomena that could not have been known by man at the time of revelation


The only way to know what God has announced to mankind is via external revelation, and this revelation can be proven to be the Qur’an – the Qur’an says “Know that your Lord God is one”.

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