The primary and fundamental essential of faith in God is to believe in His Eternal and Absolute Existence. It is the first of the four elements of faith in Allah that include the belief in His Existence, Lordship and Divinity, and in His Names and Attributes. The Prophet (peace be upon him) said, “There was Allah, and there was nothing else besides Him.” (Al-Bukhari) Those who deny the Existence of Allah are called atheists or unbelievers and they are not considered as Muslims, since the belief in this element is a basic part of faith. Unlike ours, Allah’s Existence has not been preceded by nonexistence or is vulnerable to extinction for He is the First and the Last, the Ascendant and the Intimate, and He is, of all things, Knowing.
The Concept of Existence
‘Allah’s Existence is known of the religion. It is one of the Divine Attributes according to the consensus of Muslims as well as all reasonable people, even the polytheists. Nobody disputes about except the atheists and unbelievers. The concept of existence is of two types:
First: Self-existence: That is whose existence is established in him not obtained from another being. This applies only to Allah the Almighty because His Existence has not been preceded with or susceptible to nonexistence. Almighty Allah says,
He is the First and the Last, the Ascendant and the Intimate, and He is, of all things, Knowing. (Al-Hadid 57:3)
Second: Created-Existence: It applies to those who came into existence from nothing. This type of existence applies to creatures and requires a creator to cause it to happen, who is Almighty Allah, He said,
Allah is the Creator of all things, and He is, over all things, Disposer of affairs. * To Him belong the keys of the heavens and the earth. And they who disbelieve in the verses of Allah – it is those who are the losers. (Az-Zumar 39:62-63)
Or were they created by nothing, or were they the creators [of themselves]? * Or did they create the heavens and the earth? Rather, they are not certain. (At-Tur 52:35-36)’
Ibn Al-Qayyim said in His book Madarij As-Salikin, “Almighty Allah has been singled out with Eternal Existence. He is the First that nothing preceded Him, and the Last that nothing succeeds Him. The existence of everything other than Him is based on and made by Him. He is the One with essential, right, perpetual and established Existence… His is Self-Existence… Nothing but Him is self-existed and anything else is brought by Him.”
“The evidence on the Existence of God is divided into three categories: Instinctive evidence,Tangible Evidence and Shari`ah Evidence.
1 – Instinctive evidence:
‘The instinctive evidence that God exists is the strongest evidence for those who have not been led astray by Satan. Allah says:
So direct your face toward the religion, inclining to truth. [Adhere to] the fitrah of Allah upon which He has created [all] people. No change should there be in the creation of Allah . That is the correct religion, but most of the people do not know. (Ar-Rum 30:30)
Every person feels inside himself that there is a Lord and Creator, and also feels that he is in need of Him; if some major calamity befalls him he turns his hands, eyes and heart towards the heavens, seeking help from his God.
2 – Tangible evidence:
This refers to the things that exist in this universe; we see around us a lot of things such as trees, rocks, mankind, the earth, the heavens, seas, rivers… The question is who did create and take care of them?
Did these things come into being by accident, spontaneously and with no cause? This is impossible. There must be a creator who created them, and that Creator is Allah. This is what is stated in the Qur’an, where Allah says:
Were they created by nothing? Or were they themselves the creators? Or did they create the heavens and the earth? Nay, but they have no firm Belief. (At-Tur 52:35-36)
It is Allah who has given to each thing that which is suited to it and guarantees its survival. If you ponder on the universe, it will lead you to the belief in the Existence of a Powerful Creator, the Almighty God.
3 – Shari`ah Evidence:
All divinely-revealed laws point to the Existence of Allah. Sheikh Ibn `Uthaimin said: “All the divinely-revealed laws point to the Existence of the Creator and to the perfect nature of His Knowledge, Wisdom and Mercy.” (From Sharh Al-Safariniyyah)”
Fruits of the Belief in God’s Existence
The belief in God’s Existence generates in the heart of the believer inner consciousness and observation of Allah. A believer recognizes that Allah is watchful of his whole deeds, whether publically or privately and thus abstains from committing anything that displeases His Lord. Allah says,
Have you not considered that Allah knows what is in the heavens and what is on the earth? There is in no private conversation three but that He is the fourth of them, nor are there five but that He is the sixth of them – and no less than that and no more except that He is with them [in knowledge] wherever they are. Then He will inform them of what they did, on the Day of Resurrection. Indeed Allah is, of all things, Knowing. (Al-Mujadilah 58:7)
The one believing in God feels fear of Him, attends to what pleases Him, keeps away from all that displeases Him and constantly seeks His Support, Guidance, Peace, Mercy and bountiful reward in this worldly life and the Hereafter. Almighty God maintained that His Help, Protection, Guidance, Graciousness and Bounty will be bestowed to those who believe in Him, He (Glory be to Him) says,
Allah is the ally of those who believe. He brings them out from darknesses into the light. And those who disbelieve – their allies are Taghut. They take them out of the light into darknesses. Those are the companions of the Fire; they will abide eternally therein. (Al-Baqarah 2:257)
Indeed, Allah defends those who have believed. Indeed, Allah does not like everyone treacherous and ungrateful. (Al-Hajj 22:38)
Allah is the protector of those who have believed and the disbelievers have no protector. (Muhammad 47:11)
And indeed is Allah the Guide of those who have believed to a straight path. (Al-Hajj 22:54)
They who believe and do not mix their belief with injustice – those will have security, and they are [rightly] guided. (Al-An`am 6:82)
Whoever does righteousness, whether male or female, while he is a believer – We will surely cause him to live a good life, and We will surely give them their reward [in the Hereafter] according to the best of what they used to do. (An-Nahl 16:97)
ــــــــــــــــــــــــــــــــــــــــــــــ Committee for Scholarly Research and Fatwa, KSA  Islamqa.com with modifications.
To be continued…
See also:Soucre Link