God Almighty, is a being which is absolute existence and complete perfection devoid of all deficiencies and imperfections. The concept of God is one which is very simple and clear. Everyone, including those who deny his existence, are able to comprehend and understand it. Even though the understanding of the essence and reality of God is incomprehensible for human beings, yet there are many ways of gaining knowledge of his existence. The ways of gaining knowledge of God can be divided into the mentioned categories below:
1- The way of logic (for example the proof of possibility and necessity and so on…)
2- The way of experience (for example the proof of order in creation)
3- The way of the heart (for example the proof of our innate nature)
The easiest and simplest of ways is that of the proof of our innate nature (knowing God through the heart). Human beings, by returning to their inner self, become needless of all manners of logical or experiential proofs and are able to know God and gain access to Him through the heart. As to the question of how he came into creation or who created him, the answer can be resolved through resorting to philosophy. In philosophy it is said that: “What is the criterion for the need of a cause?” Scholastic theologians, in the matter of the criterion for the need of a cause for something taking place, have placed their finger on the matter of huduth, but in philosophy the original criterion of the need of a cause has been considered to be imkan. From their perspective, they have considered the essence of God as devoid of the characteristic of imkan, thus the question of who His cause is, isn't even applicable to Him and in other words, asking of who created Him and who His cause is, is an illogical question (because this question can only be asked about things that bear the characteristic of imkan).
In order to describe the proofs of God’s existence there is a need to first delve into several important points.
1- The basic concept of God’s existence is a concept which every human being, including those who deny his existence, are able to comprehend and understand. Everyone knows that the concept of God means the existence of a being who is the creator of all of the creation, who is powerful in all ways, aware of all things, all seeing, all hearing, living, alive, and etc… Even people who deny such a being can still imagine Him mentally and comprehend Him.
2- However much the basic concept of God is the most general of all concepts and easily understandable, gaining an understanding of his essence (Dhaat) and reality is not possible for human beings. This is because his essence is unlimited and infinite, while for us to have knowledge of a thing means to contain and surround it with our minds, and our minds are limited, and the limited cannot contain the unlimited. A verse in the Quran says, (لا یحیطون به علما), which means that they will never be able to encompass God’s knowledge, and it may be for this very reason that the Holy Quran introduces God through the characteristics of beauty and majesty such as: the knowledgeable, the wise, the all hearing, the all seeing, the most high, the most merciful, the most gracious, the most great, the creator, the originator, and the self sufficient.
In addition to this, we understand the world around us through our senses, while Allah (swt) is intangible (the Quran mentions: لیس کمثله شی , which means that there is nothing like him) making it is impossible for human beings to completely comprehend him.
3- Even though gaining access to the reality and essence of God is not possible, still there are many ways of gaining certitude in God’s existence. These ways can be broken down as follows:
A- The way of logic (for example the proof of possibility and necessity and so on…)
B- The way of experience (for example the proof of order in creation)
C- The way of the heart (for example the proof of our innate nature)
4- The easiest and simplest of ways is that of the proof of our innate nature (knowing God through our inner nature and heart). This means that inside of every person there exists a spiritual side, an understanding, and an inclination towards love of the creator. There always exists a point of connection between the human being and God in the heart of each individual.
5- Even though the understanding of God and his oneness is something which is built into the inner nature of man, still the various prevailing cultures, superstitions, incorrect ideologies, pride, and deviation (especially in the face of superabundant blessings and health from God) can all act like a curtain and conceal this inner nature. It is only when problems and disasters take place for man, leaving him hopeless of all things and showing him that nothing can save him, that these curtains once again move aside, revealing that luminous part of the soul and allowing him to reconnect with his original nature. These hardships and disasters purify him of the impurities blocking him from turning to the above. For this same reason, the Holy Quran mentions the blessing of man’s inner nature through this matter (of how it is when man suffers from problems and dangers that he turns to Allah (swt)) multiple times throughout its verses.
The Imams (a) would educate those who were in doubt about the existence of God using these same methods. As an example, refer to this historical piece:
A man who was perplexed in the matter of understanding God and was beset with doubts and uncertainties, presented himself to Imam Sadiq (a) and said the following: Oh Son of the Prophet of God (s), guide me towards the concept of God….What is God? People who doubt in his existence have confused me. The Imam (a) said: Oh servant of God! Has it ever occurred where you rode on a ship? The man replied: Yes. Imam (a) said: While you were riding on a ship did it ever occur where your boat began to sink, while there were no other boats to rescue you and you didn’t have the ability to swim to save yourself? The man again replied: Yes, this has happened to me. Imam (a) said: At that time, did your heart feel that there was a being in existence who could save you from that perilous situation? The man again replied: Yes. Imam Sadiq (a) then said: That being, who is able to save you when there is no one else to save you and no one to hear your cries is God!
This shows that every human being is able to use his heart and inner nature to understand and comprehend a God who is powerful, knowledgeable, living, and kind. Even beyond this basic understanding, man will also be able to have a connection and inclination towards this being. Even for those who reject the existence of God, you cannot find a person who, at some time or another, has not been in a precarious situation that made him aware of the existence of God.
6- Sometimes people, through detailed study and thought, and pondering the relationships between different phenomena, are guided to the characteristics of God (such as knowledge, wisdom, and power). This way of finding and knowing God, since it’s based on the proofs of the natural world and its study, is known as the experiential method of proving God. Due to the advantages of this path, the Holy Quran has given it special considerations, and in many verses, it has encouraged man to ponder over the natural world and its various signs and manifestations. Some Islamic researchers, by pointing to the order in the world’s creation, have used this as a proof for God’s existence and this is called the ‘The Proof of God in the Order of Creation’. Based on this, we can consider this ‘Proof of Order’ to be one of the examples of the experiential method of knowing God.
Understanding through the ‘signs’ pointed to in the Quran and hadiths
All over the Quran, verses can be found that point to different phenomena of this world, which are all considered signs of Allah’s (swt) existence. They encourage people towards reflecting and pondering over these signs. Sometimes this method of proving the existence of God is called the “Understanding of God through signs and ‘horizons’”.
Some groups of verses in the Quran encourage people towards reflecting on the outer signs of the natural world and the order which is present in God’s creation and in our creation; these are used as evidence and guidance for the people who are wise and who use their intellect. For example: “Behold! in the creation of the heavens and the earth, and the alternation of night and day,- there are indeed Signs for men of understanding.”
Another verse says: “On the earth are signs for those of assured Faith, as also in your own selves: will ye not then see?”
A large number of the verses from the Quran point specifically to certain natural phenomena and they use these as a sign of the existence of God and of his knowledge and divine power. These verses are so abundant that to mention even some of them would entail a difficult and comprehensive endeavor. The Imams (a), in following the methods of the Quran, have emphasized the recognition of God’s signs. For example, in a comprehensive tradition by Imam Sadiq (a), which was addressed to one of his companions, it has been narrated that he said: “Oh Mufadhal! The first example and proof for the existence of God (Praised and Glorified) is the life we see in this world and the order in its creation. If we were to ponder deeply over the creation of this world, then you would see that all of the needs of the servants of God have been gathered and made ready for them. The sky is made like a tall ceiling; the earth is spread out like a carpet; the stars are like lights which have been arranged, its treasures have been concealed in it; everything has been arranged in its own appropriate place. This is a home which human beings have been given and everything which they need has been given to them for their use. All manners of plants and animals exist for their use. These are all proofs that the world was created in exact proportions and it was created wisely, with order and harmony, and coordination. Its creator is the one who has given this world shape, order, and coordination.”
7- The Way of Logic: in this path, the existence of God is proven through the help of premises, principles, and other purely logical methods.
Philosophical evidence and proofs of the existence of God are good examples of how there have been efforts in this field as well. This method, in comparison with the two previously mentioned methods, has certain particularities which we will mention below:
A- Many of the philosophical arguments and logic based explanations are of not much use for people who do not have a familiarity with philosophy.
B- One of the advantages of the logical method is that in debates with atheists or skeptics, it can be used to show the weakness of their arguments in very clear terms. Also for those who do not accept any proofs but logic based ones, this method is again very useful.
C- The logical method of gaining an understanding of God can be very useful in strengthening faith. Whenever human wisdom and intellect becomes humbled in the face of a reality, the heart becomes stronger. In addition, eliminating doubt through ration and intellectual reasoning plays a great role in the prevention of the weakening of faith.
Taking into consideration the unique function of the intellectual method, and the mind’s natural inclination towards profound intellectual matters and discussions, Islamic scholars have made great efforts regarding understanding God through logic and intellect which have led to new arguments in this field, or the completion of previous ones. One of the most solid logic based reasons for proving the existence of God is the famous proof called “The Argument of Necessity and Possibility” (wujub wa imkan). There are different variations to this argument, but for our purposes we will use the one below. We can summarize this proof of necessity and possibility in this format: It is certain that there exists a being in the universe. If this being is the necessary existent, then our proof will be at hand. If it is a possible existent, then it has a need for a cause and since it is impossible to have an infinite chain of possible existents, this possible existent is in need of a necessary existent (whose existence is not bestowed by another cause). This existent is that of the Wajibul Wujud, or the necessary existent. To repeat this in other words, there are different kinds of possible existents in the world. They are either necessary existents or possible existents. The necessary existent does not derive its being from another cause or being, but the possible existent came into being due to another cause. All possible existents go back in a chain that must lead to a necessary existent, due to the fact that an infinite chain of existents is impossible.
The other part of the question asked: How did God come into being and who created him? In the quest to answer this, it must be said that there is a false line of reasoning here that sometimes confuses people. In reality, it must be said that everything which exists and has been created needs a creator and in philosophical terms, every possible existent (mumkinul-wujud) needs a necessary existent (wajibul-wujud). God’s essence is not a created phenomenon for us to ask who created it. In philosophical terms we say that God is not a possible existent to need a reason or have a need for a reason behind his existence; God is a necessary existent.
For further explanation, we should refer back to this original question: What is the criterion for needing a reason? Theologians argue that it is the matter of huduth (taking place) that makes something in need of a reason and cause. Therefore, if a phenomenon is something which never took place (ancient) then the question does not apply to it.
Philosophers however, believe that it is imkan (possibility) that makes a thing in need of a cause; since the essence of God is excluded from this term of possibility and is a necessary existent, therefore it is outside of needing a reason for its existence.
As we can see, neither scholastic theologians nor philosophers see the criterion for being in need of a reason as existence itself, meaning that the criterion of the need for a reason is not meant to mean that everything which exists must necessarily have a cause for its existence. They have said that every hadeth being, or mumkin existent, is in need of a reason for existing. Based on this line of thinking it can’t be said that since God exists then he must have a reason for existing. Therefore, the criterion for the need of a reason is a characteristic which does not include God, because He is neither hadeth nor mumkin, so he is in no need of a cause. For more information on this issue of the reasons for existence, please refer to the sources below:
1- The Unity of God, by Murteza Muttahari
2- The World View of the Unity of God, by Murteza Muttahari
3- Explaining the Proofs of God’s Existence, by Ayatollah Javadi Aamoli
 Surah Taha, Verse 110.
 Tafseere Nemoneh, Volume 14, Page 161.
 Surah Shura, Verse 11.
 Just because this method is named the experimental method, doesn’t meant that it is devoid of ration and reasoning, what the name denotes is that one of the main premises of this argument is based on making observations of natural phenomena in this world.
 Ma’arefe Eslami, vol. 1, pg. 41.
 Tafseere Nemoneh, Volume 16, Pages 341 and 342
 Ibid, pp. 418-422 and 423.
 Like Ankabut:65, Rum:30, Yunus:12, 22 and 23, Isra:67 and Zumar:8 and 49.
 Biharul-Anwar, vol. 3, pg. 41.
 Let it not be left unsaid that there are different interpretations regarding the “Understanding through signs” that comes from the Quran: Some see it as a preliminary step to a logical argument – similar to what we had in the argument of the order of creation – that proves Allah’s (swt) existence and wisdom. Others believe that when verses of the Quran invite us to ponder natural phenomena, all that is happening is that our innate knowledge and tendency towards Allah (swt) is being revived and awakened; we are being reminded of things we already know of and have. Yet a third group say that verses like these are a form of jidal ahsan (disputing in a good manner) with the mushriks; those who thought their false Gods had some say in the affairs of this world and had a wrong perception of Allah's (swt) tawhid. (See: Al-Mizan, Allamah Tabatabai, vol. 18, pg. 154; Amuzesh Aqa’id, Misbah Yazdi, vols. 1-2, pg. 68; Tabyine Barahine Esbate Khoda (A Commentary On Theistic Arguments), Javadi Amoli, pg. 43).
 “ان فی خلق السماوات والارض و اختلاف اللیل والنهار لآیات لاولی الالباب” (Ale Imran:190).
 “و فی الارض آیات للموقنین. و فی انفسکم، افلا تبصرون” (Dhariyat:20 and 21. Also see: Baqarah:164; Jathiyah:3-6; Yunus:100 and 101; Ibrahim:10).
 The verses that emphasize on certain phenomena being signs can be categorized into several general groups. Verses that have to do with the human being have the following categories:
a) The order of the creation of man: Jathiyah:4 and Rum:20.
b) The formation of the sperm in the womb: Ale Imran:6; Infitar:6-7; Taghabon:3; Ghafir:64; Hashr:24; Nuh:13-14
c) The system of knowledge: Nahl:78
d) The diversity of languages and colors: Rum:22; Fatir:27-28;
e) Sustenance: Ghafir:64; Isra:70; Jathiyah: 5 and 20; Fatir:3; Rum:4; Saba’:24; Yunus: 31; Naml:64; Mulk:21; Anfal:26; Baqarah: 22 and 172; Ibrahim:22 and Dhariyat:58
f) Man’s sleep: Rum:23; Naml:86; Rufqan:47; Naba’:9 and Zumar:42
g) Man’s clothing: A’raf: 26 and Nahl:14 and 81
h) Man’s habitation: Nahl:80
i) Marriage: Rum:21; Shura:11; Fatir:11; Najm:45; Qiyamah: 39; Nahl: 72; Leyl:3; Naba’:8 and A’raf:189.
 Also see: Nahjul-Balaghah, sermon 186; Al-Tawhid, Sheikh Saduq, chapter 2, hadith 2; Biharul-Anwar, Allamah Majlisi, vol. 3, pp. 61, 82, 130, 152.
 Just because this method has been named the intellectual or logical method, doesn’t mean that only the intellect works here, what is meant is that in the premises only intellectual matter have been utilized.
 This isn't in conflict with what is said about the way of the mind being universal and general, because what is meant by generality here is relative generality as opposed to being “personal”, meaning that the way of the mind isn't peculiar to one specific person and everyone can use it.
 The way of the mind can be especially beneficial to those who don’t bear inner disclosure of Allah (swt) or don’t see Him with the eyes of their hearts.
 Adopted from Question 1041 (The fitrah and understanding Allah).
 Shafi’i Mazandarani, Seyyed Mohammad, Mabda’ Shenasi, pp. 146-147.