Let's consider some positive arguments for the existence of spirit beings.
• Matter serves life, not the other way around. Science cannot explain life or how organic matter acquires life. Although matter appears to be the basis for or serves as a receiver of life, it is clearly not its originator. So, life is sent from the immaterial dimensions of existence. God infuses it into matter or inorganic substances via something immaterial and invisible. We call this spirit. The particular features of each spirit makes each individual unique, although they are formed of the same physical elements.
• Life does not depend on matter. On the contrary, life makes a tiny body greater than a huge one. For example, life makes a fly or a bird greater than a mountain. Life enables a honeybee to claim the Earth as its garden, establish relations with all flowers, and enter into transactions with them. Again, the more refined matter is, the more developed and active life is. Life's development and activity has nothing to do with physical size A fly or a flea is more active and has sharper senses than a camel or rhinoceros.
• This world is the arena in which God manifests His Will through natural causes. But life is the result of the direct manifestation of His Name the Ever-Living. Thus, as long as science insists on its positivistic, even materialistic, viewpoint, it will never penetrate the mystery of life. [*]
Reality and wisdom in the existence of the universe require that the heavens should have conscious inhabitants of their own, as does the Earth. These inhabitants of many different kinds are called angels and spirit beings in the language of religion.
It is true that reality requires the existence of angels and other spirit beings because the Earth, although insignifi-cant in size compared with the heavens, is continually being filled with and emptied of conscious beings. This clearly indicates that the heavens ... are filled with living beings who are the perfect class of living creatures. These beings are conscious and have perception, and they are light of existence; they are the angels, who, like the jinn and mankind, are the observers of the universal palace of creation and students of this book of the universe and heralds of their Lord's Kingdom.
The perfection of existence is through life. Moreover, life is the real basis and the light of existence; consciousness, in turn, is the light of life. Since life and consciousness are so important, and a perfect harmony evidently prevails over the whole creation, and again since the universe displays a firm cohesion, and as this small everrotating sphere of ours is full of countless living and intelligent be-ings, so it is equally certain that those heavenly [realms] should have conscious, living beings particular to themselves. Just as the fish live in water, so those spirit beings may exist in the heat of the sun. Fire does not consume light; rather, light becomes brighter because of fire. We observe that the Eternal Power creates countless living beings from inert, solid substances and transforms the densest mater into subtle living compounds by life. Thus It radiates the light of life everywhere in great abundance and furnishes most things with the light of consciousness.
From this we can conclude that the All-Powerful, All-Wise One would certainly not leave without life and consciousness more refined, subtle forms of matter like light and ether, which are close to and fitting for the spirit. Indeed He creates animate and conscious beings in great numbers from light, darkness, ether, air and even from meanings and words. As He creates numerous species of animals, He also creates from such subtle and higher forms of matter numerous different spirit creatures. One kind ... are the angles, others are the varieties of spirit beings and jinn. [Said Nursi, The Words 1 (Turestar, 1993), 113-17.]
Half a century after Said Nursi wrote this, nearly 300 animal species, almost all of them previously unknown, have been discovered living around hydrothermal vents that form when seawater leaking through the ocean floor at spreading ridges is heated by the underlying magma and rushes into the cold ocean.
V. Tunniclife writes:
All life requires energy, and nearly all life on Earth looks to the sun as the source. But solar energy is not the only kind of energy available on the Earth. Consider the energy that drives the movement and eruption of the planet's crust. When you look at an active volcano, you are witnessing the escape of heat that has been produced by radioactive decay in the Earth's interior and is finally reaching the surface. Why should there not be biological communities associated with the same nuclear energy that moves continents and makes mountains? And why could not whole communities be fuelled by chemical, rather than, solar energy?
… Most of us associate the escape of heat from the interior of the Earth with violent events and unstable physical conditions, with extreme high temperatures and the release of toxic gassescircumstances that are hardly conducive to life. The notion that biologic communities might spring up in a geologically active environment once seemed fantastic. And until recently, few organisms were known to survive without a direct or indirect way to tap the sun's energy. But such communities do exist, and they represent one of the most startling discoveries of 20th century biology. They live in the deep ocean, under con-ditions that are both severe and variable.
This startling discovery contains clues to other realities, which science should consider. Prophet Muhammad, upon him be peace and blessings, states that angels are created from light. We read in the Qur'an that God created humanity from dried soil, wet clay, and an extract of clay, and then made humanity His khalifa [one who comes after (to rule according to God's commandments)] for this planet. Many interpreters of the Qur'an have concluded from this that jinn once ruled Earth and were succeeded by humanity.
Starting from the clues above, it should be possible to do formal studies to determine the worth of such propositions as the following:
• God first created "pure light" (nur) and then light. The process of creation followed a gradual, regular accumulation of identities and/or an evolutionary sequence of abrupt leaps. Fire followed light, and then came water and soil. God spread one existence through another, compounding and interweaving, and created liv-ing beings appropriate for each phase of creation. When the universe was in a state of pure fire or some other high energy, He created appropriate life forms. When the Earth became suitable for life, He created plants, animals, and humanity. He adorned every part and phase of the universe with creatures, including living ones, appropriate for that part and phase.
• Finally, just as He created innumerable beings from light, ether, air, fire, water, and soil, so does He create Paradise or Hell from each of our words and deeds. In other words, just as He grows a tree from a tiny seed through particles of soil, air and water, so will He build the other world, including Paradise and Hell, from the material of this world by adapting it for the other world during the convulsions of the Day of Judgment. [The Fountain, No. 13 (Jan.-March 1996), pp. 36–37.]
• Angels are pure spirit beings that represent the purely good aspect in existence, while Satan and his minions represent the purely evil aspect. God is One and Infinite, without opposite. All other beings and existents have an opposite. Therefore, angels represent our good aspect while Satan represents our evil aspect. Angels invite us to our purely spiritual or "angelic" aspect, while Satan tempts toward evil. The resulting struggle, both in us and in the universe as a whole, has been ongoing since the beginning of existence. Everyone feels a stimulus toward good and evil at the same time. The former comes from the angels or our unpolluted spirit; the latter comes from Satan collaborating with our carnal self, which represents our animal aspect.
• This spiritbody relation can be likened to that between electrical power and a factory run by electricity. If there is no electricity, the factory is reduced to heap of junk. Likewise, when the spirit leaves the body because of some rupture or disconnection (e.g., illness or death), we become no more than a mass of tissue and bone that decomposes in the soil. This shows that our real existence and uniqueness depend on this spirit.
• We accept the existence of natural laws and forces unquestionably, and even go so far as to attribute all phenomena to them. We ascribe a tiny seed's growth into a huge, elaborate tree to the law of germination and growth in that seed, and the universe's incredible balance to the laws of gravitation and repulsion. But we ignore the absolute will, knowledge, power, and wisdom necessary for the universe's very existence, operation, and balance. The One Who has absolute Will, Knowledge, Power, and absolute Wisdom uses such powerful invisible beings (angels) as winds or gales, and others much more powerful than natural forces or laws, behind natural forces and laws to make them operative.
• In addition to religious scholars, almost all Muslim philosophers and even all Oriental philosophers agree that angels and spirit beings exist. They just have different names for them. The Peripatetic (Mashshaiyyun) school of philosophy, although quite inclined toward rationalism and even materialism, admitted the existence of angels on the grounds that each species has a spiritual, incorporeal essence. The Illuminists (Ishraqiyyun) also accepted the existence of angels, calling them (wrongly) the "Ten Intellects and Masters of Species." On the other hand, followers of all Divine religions, guided by Divine Revelation, believe that there is an angel in charge of each type of existence, and name them accordingly: the Angel of the mountains, the Angel of the seas, the Angel of rain, and so on. Even naturalists and materialists, who restrict themselves to what they see, admit the meaning of angels, which they call pervasive forces. 
• All Prophets, numbering 124,000 in reliable religious sources, report the existence of angels, spirit beings, jinn, and Satan. All saints and religious scholars agree on this invisible realm's existence. We hardly need to say that two specialists in a matter are preferable to thousands of non-specialists. In addition, it is an established fact that once a matter is confirmed by two people, its denial by thousands of others has no weight. Furthermore, all people of religion and followers of almost all religions accept the existence of such beings.
All Divine Scriptures record the existence of spirit beings and the human spirit, as well as the story of Satan and how he tempts us. Above all, can one doubt the report of the Qur'an and the testimony and experiences of Prophet Muhammad, upon him be peace and blessings? The proofs of the Qur'an's Divine authorship, the mission of Prophethood, and the Prophethood of Muhammad and all other Prophets, upon them be peace, also prove the invisible realm's existence and thus the existence of the spirit, angels, jinn, and Satan.
The best and most rational way of establishing the existence of such beings is expounded by Islam, described by the Qur'an, and was seen by the Prophet, upon him be peace and blessings, during his Ascension through the heavens. The Qur'an explains the meaning of angelic existence so reasonably that anyone can understand it. In brief, it says that humanity is a community responsible for carrying out the Divine Commandments issuing from the Divine Attribute of Speech, and that angels are a community whose "working class" carry out the Divine Laws of nature issuing from the Attribute of Will. They are God's honored servants who do whatever He commands. The existence of angels and other spirit beings can be established by proving the existence of one angel. As denying one amounts to denying the species, accepting one requires accepting the species.
• A consensus has formed, especially among followers of religions, that there have always been people who can see and converse with angels, jinn, Satan, and other spirit beings. Had angels not existed, had one angel never been seen or their existence established through observation, how could such a general belief continue? If this belief were not based on strong evidence, could it have come down to us despite changing ideas and beliefs and the passage of time? Therefore, we can conclude that religious belief in the existence of such beings is based on the experiences that the Prophets and other saintly persons have had with them. Such accounts have been narrated by reliable sources.