We see clearly that extensive interrelatedness and harmony exist among all the components of the world. Man produces a carbonic gas that enables plants to breathe, and trees and plants, reciprocally produce oxygen that enables man to breathe. As a result of this interchange between man and plants, a certain amount of oxygen is preserved at all times; were it not to be so, no trace of human life would remain on earth.
The amount of heat received by the earth from the sun corresponds to the need of living beings for heat The speed of the earth's rotation around the sun and the distance it keeps from that source of energy and heat have been fixed at a level that makes human life on earth possible. The distance of the earth from the sun determines a degree of heat that exactly corresponds to the needs of life upon earth. Were the speed of the earth's rotation to be a hundred miles an hour instead of a thousand miles an hour, as it now is, our nights and days would be ten times as long, and the intensity of the sun's heat would rise to the point that all plant life would be burnt and the cold nights of winter would freeze all fresh shoots in the ground.
If, on the one hand, the rays of the sun were to be reduced by half, all living beings would be frozen in place by the extreme cold.
If, on the other hand, they were to be doubled, the sperm of life would never come to fruition. If the moon were farther away from the earth, the tides would become strong and fierce enough to uproot the mountains.
Seen in this light, the world appears to be a caravan in which all the travellers are joined together like links in a chain. All of its parts, big or small, are striving cooperatively to advance in a single direction. Throughout this organism, everything fulfills its particular function and all things aid and complement each other. A profound and invisible link joins every single atom to all other atoms.
A world that is thus replete with unity must necessarily be connected to a single source and principle. Being derives from a single origin; if the entirety of the universe is one, its creator must also be one. The fact that the creator has brought forth unity within the multiplicity of the created world is in itself a convincing proof of His oneness, power and wisdom.
The Quran says: "Ask them, 'Show me these partners whom you worship in place of God. Have they created anything from earth or have they shared with God in the creation of the heavens ? Have we given them a book on which they rely in their ascription of partners to us?' No, the wrongdoers deceive each other with their false promises. Certainly it is God Who preserves the heavens and the earth from collapse and annihilation; were they about to collapse and be annihilated, there is none other who could preserve them. Know that God is most forbearing and forgiving."(35:40-41)
Our innate nature, which is a fundamental dimension of our existence, also confirms the oneness of God. In severe crises and times of hardship, our desires are all focused on one point; we turn in one direction and entrust our hearts to Him.
One of the pupils of Imam Ja'far Sadiq, upon whom be peace, asked him, "What proof is there for the oneness of God?" The Imam answered him: "The proof of His oneness is the interrelatedness and continuity of all creation, the integral order of being that rules over all things. God says in the Quran: 'Were there a creator in the heavens and earth other than the One God, their order would vanish and the world would be destroyed.'"[10]
So the regularity and comprehensiveness of the order that ruled over all things refutes the theory that there might be several gods, ruling the same or different spheres.