One of the attributes of God is Unity, which is stressed by certain religions, especially Islam. Monotheism and belief in Oneness of God is one of the prominent characteristics of Islam, for which it has been named the religion of monotheism. Theological philosophers have also always believed in monotheism, and have resorted to following arguments to prove the unity of God.
1. Necessity of existence leads us to conclude that there must not be more than one Necessary Being; because whenever we talk of two or more things, it is necessary that those two things should possess some points of similarity, on the one hand, and some points of difference, on the other.
For example, when we talk of two books, it is necessary that, firstly, they have something in common in that they are both `books', and, secondly, differ in at least one respect; otherwise, if they are similar in colour, appearance, weight, size, author, paper, subject matter, time, place and all other peculiarities, they cannot be considered as two books and can only be one and the same book.
Therefore, every sort of plurality has certain points in common, on the one hand, and differences, on the other. Now if we suppose that two or more gods exist, then they must have at least one aspect in common and one or more aspects of difference. That is, each one of them must have one thing in common with the other and also have a point or points especial to itself.
Therefore, each one of them has a compounded being composed of at least two aspects or characteristics, and each compound would require its own components on whose existence its own existence depends. It is obvious that a being which is compound is dependent for its existence on its parts, and hence is not self‑existing. This is contradictory to the definition of the Necessary Being. Accordingly, the assumption that there can be two or more Necessary Beings leads to a self‑contradiction.
2. The orderly state of the universe, of necessity, shows that its creator cannot be more than one; because, if such were the case, there would have been a difference of essence and natures between creators. Moreover, two or more creators of differing essences and natures will necessarily produce different and divergent effects depending on the manner of relationship of these effects with the differing will of the creators.
Further, it is obvious that two or more different entities possessing differing wills would offer differing schemes for the order of the universe‑an order which in reality is an interconnected, integrated unit. Also, their varying wills and plans for creation would necessarily cause disorder, leading to ultimate destruction. The Holy Quran states this point:
لَوْ كَانَ فِيهِمَا آلِهَةٌ إِلاَّ اللَّهُ لَفَسَدَتَا فَسُبْحَانَ اللَّهِ رَبِّ الْعَرْشِ عَمَّا يَصِفُونَ
If there had been in them (heavens and earth) any gods except Allah, they would both have certainly been in a state of disorder. (21:22)
The late `Allamah Tabataba'i, in his commentary on this verse, writes:
“In our commentary on Surat Hud, and also subsequently, we have made it clear that the controversy between the idolaters and the monotheists does not relate to the issue of unity or plurality of the Necessary Being; because, that the Necessary Being is one and without divine associates is not a matter of dispute; rather, the dispute concerns God as the deity worthy of worship.
Idolaters contend that administration of the world with its multiple affairs has been delegated to noble beings such as god of the heavens, god of the earth, and god of human beings, all of whom have nearness and access to God; they must be worshipped, so that they may intercede with God on behalf of their worshippers and thus bring them near to God. They are gods of beings inferior and subject to their authority, and Allah, the god of gods, is the creator of everything. As the Quran, in this regard, says: "And if you ask them `who is the creator of the heavens and the earth, they will say `Allah',... and if you ask them who has created the heavens and earth they will say `the Powerful and the Wise has created them'."
The verse under discussion negates these gods in this sense, not in the sense of their being creators or makers; for no one had insisted on a belief in plurality of creators.
However, the obvious import of the verse is that if there were more than one God, they would differ as to their essence and nature, and such difference would be tantamount to departure in their schemes, resulting in their mutual destruction and disorder throughout the system of the heavens and the earth. But the existing order of the universe is a unified one, whose parts and components are in coordination and harmony with one another and in conformity with its purposes. Therefore, there cannot be more than one God.
Another verse cited in relation to the proof of the Unity of God, is the following:
مَا اتَّخَذَ اللَّهُ مِنْ وَلَدٍ وَمَا كَانَ مَعَهُ مِنْ إِلَٰهٍ إِذًا لَذَهَبَ كُلُّ إِلَٰهٍ بِمَا خَلَقَ وَلَعَلَا بَعْضُهُمْ عَلَىٰ بَعْضٍ سُبْحَانَ اللَّهِ عَمَّا يَصِفُونَ
God has not taken to Himself any son, nor is there any god besides Him; for then each god would have taken off that he created and some of them would have risen up over others; glory be to God, beyond that they ascribe [to Him]. (23:91)
The purpose of this verse is apparently to state that if we suppose two gods as existing, some kind of difference between them is inevitable; for two distinctly separate beings entail that they differ at least in one respect. As stated in connection with the preceding verse, will is also one of the essential characteristics of these two beings. Accordingly, a universe subject to two differing wills, would inevitably result in disorder and discord; because each one of the gods with a separate will of his own would act independently of the other and in accordance with his own will.
That is, the verse implies that if there were two gods, each one of them would have governed his creation according to his own will, and, consequently, no order whatsoever could be established in the universe, since the creation of each god would differ from that of the other, and, as a consequence, integration, order and coordination would not exist, or granting that some kind of order could be achieved, sooner or later it would come to naught and would not endure. This is the case if neither of the two or more gods is subordinate to another but each one of them administers a part of the universe independently.
But the observable order of the universe is the best witness of the fact that the universe is governed by a single hierarchy of laws; that is, though some sections of the universe are subject to some special laws (such as the plant kingdom and animal kingdom), they, in addition to their particular laws, are governed by the general laws of the universe (the law of gravitation, for example).
Now if we attribute each one of these kingdoms with their special, more general, and most general laws to each of the gods, each one of them would inevitably be subordinate to the superior god, and, as a matter of course, each would become a tool for realization of the actions and objectives of the superior god. However, such beings cannot be called `gods', since they are effects among various effects. This is what is meant when the above verse states `some of them would have risen over others.'
This proof of monotheism, which was obtained from the proof of order, demonstrates the Unity of Divine sovereignty (tawhid rububi); that is, by demonstrating that there is a single unitary order prevailing in the universe, it proves that the universe is administered by one Designer and Sovereign.
The unity of the Divine Sovereign, of necessity, leads to monotheism in worship; because worship is directed towards a Divine sovereign, and if He is one, then worship is addressed solely to Him‑not to numerous sovereigns. Accordingly, unity of divinity, divinity being a necessary counterpart of sovereignty, and sovereign of the universe being the same as its god‑is proved: the universe has one God and one Sovereign.
1. Necessity of existence leads us to conclude that there must not be more than one Necessary Being; because whenever we talk of two or more things, it is necessary that those two things should possess some points of similarity, on the one hand, and some points of difference, on the other.
For example, when we talk of two books, it is necessary that, firstly, they have something in common in that they are both `books', and, secondly, differ in at least one respect; otherwise, if they are similar in colour, appearance, weight, size, author, paper, subject matter, time, place and all other peculiarities, they cannot be considered as two books and can only be one and the same book.
Therefore, every sort of plurality has certain points in common, on the one hand, and differences, on the other. Now if we suppose that two or more gods exist, then they must have at least one aspect in common and one or more aspects of difference. That is, each one of them must have one thing in common with the other and also have a point or points especial to itself.
Therefore, each one of them has a compounded being composed of at least two aspects or characteristics, and each compound would require its own components on whose existence its own existence depends. It is obvious that a being which is compound is dependent for its existence on its parts, and hence is not self‑existing. This is contradictory to the definition of the Necessary Being. Accordingly, the assumption that there can be two or more Necessary Beings leads to a self‑contradiction.
2. The orderly state of the universe, of necessity, shows that its creator cannot be more than one; because, if such were the case, there would have been a difference of essence and natures between creators. Moreover, two or more creators of differing essences and natures will necessarily produce different and divergent effects depending on the manner of relationship of these effects with the differing will of the creators.
Further, it is obvious that two or more different entities possessing differing wills would offer differing schemes for the order of the universe‑an order which in reality is an interconnected, integrated unit. Also, their varying wills and plans for creation would necessarily cause disorder, leading to ultimate destruction. The Holy Quran states this point:
لَوْ كَانَ فِيهِمَا آلِهَةٌ إِلاَّ اللَّهُ لَفَسَدَتَا فَسُبْحَانَ اللَّهِ رَبِّ الْعَرْشِ عَمَّا يَصِفُونَ
If there had been in them (heavens and earth) any gods except Allah, they would both have certainly been in a state of disorder. (21:22)
The late `Allamah Tabataba'i, in his commentary on this verse, writes:
“In our commentary on Surat Hud, and also subsequently, we have made it clear that the controversy between the idolaters and the monotheists does not relate to the issue of unity or plurality of the Necessary Being; because, that the Necessary Being is one and without divine associates is not a matter of dispute; rather, the dispute concerns God as the deity worthy of worship.
Idolaters contend that administration of the world with its multiple affairs has been delegated to noble beings such as god of the heavens, god of the earth, and god of human beings, all of whom have nearness and access to God; they must be worshipped, so that they may intercede with God on behalf of their worshippers and thus bring them near to God. They are gods of beings inferior and subject to their authority, and Allah, the god of gods, is the creator of everything. As the Quran, in this regard, says: "And if you ask them `who is the creator of the heavens and the earth, they will say `Allah',... and if you ask them who has created the heavens and earth they will say `the Powerful and the Wise has created them'."
The verse under discussion negates these gods in this sense, not in the sense of their being creators or makers; for no one had insisted on a belief in plurality of creators.
However, the obvious import of the verse is that if there were more than one God, they would differ as to their essence and nature, and such difference would be tantamount to departure in their schemes, resulting in their mutual destruction and disorder throughout the system of the heavens and the earth. But the existing order of the universe is a unified one, whose parts and components are in coordination and harmony with one another and in conformity with its purposes. Therefore, there cannot be more than one God.
Another verse cited in relation to the proof of the Unity of God, is the following:
مَا اتَّخَذَ اللَّهُ مِنْ وَلَدٍ وَمَا كَانَ مَعَهُ مِنْ إِلَٰهٍ إِذًا لَذَهَبَ كُلُّ إِلَٰهٍ بِمَا خَلَقَ وَلَعَلَا بَعْضُهُمْ عَلَىٰ بَعْضٍ سُبْحَانَ اللَّهِ عَمَّا يَصِفُونَ
God has not taken to Himself any son, nor is there any god besides Him; for then each god would have taken off that he created and some of them would have risen up over others; glory be to God, beyond that they ascribe [to Him]. (23:91)
The purpose of this verse is apparently to state that if we suppose two gods as existing, some kind of difference between them is inevitable; for two distinctly separate beings entail that they differ at least in one respect. As stated in connection with the preceding verse, will is also one of the essential characteristics of these two beings. Accordingly, a universe subject to two differing wills, would inevitably result in disorder and discord; because each one of the gods with a separate will of his own would act independently of the other and in accordance with his own will.
That is, the verse implies that if there were two gods, each one of them would have governed his creation according to his own will, and, consequently, no order whatsoever could be established in the universe, since the creation of each god would differ from that of the other, and, as a consequence, integration, order and coordination would not exist, or granting that some kind of order could be achieved, sooner or later it would come to naught and would not endure. This is the case if neither of the two or more gods is subordinate to another but each one of them administers a part of the universe independently.
But the observable order of the universe is the best witness of the fact that the universe is governed by a single hierarchy of laws; that is, though some sections of the universe are subject to some special laws (such as the plant kingdom and animal kingdom), they, in addition to their particular laws, are governed by the general laws of the universe (the law of gravitation, for example).
Now if we attribute each one of these kingdoms with their special, more general, and most general laws to each of the gods, each one of them would inevitably be subordinate to the superior god, and, as a matter of course, each would become a tool for realization of the actions and objectives of the superior god. However, such beings cannot be called `gods', since they are effects among various effects. This is what is meant when the above verse states `some of them would have risen over others.'
This proof of monotheism, which was obtained from the proof of order, demonstrates the Unity of Divine sovereignty (tawhid rububi); that is, by demonstrating that there is a single unitary order prevailing in the universe, it proves that the universe is administered by one Designer and Sovereign.
The unity of the Divine Sovereign, of necessity, leads to monotheism in worship; because worship is directed towards a Divine sovereign, and if He is one, then worship is addressed solely to Him‑not to numerous sovereigns. Accordingly, unity of divinity, divinity being a necessary counterpart of sovereignty, and sovereign of the universe being the same as its god‑is proved: the universe has one God and one Sovereign.