There are seven (7) essentials to basic Islamic faith not believing in one of these essentials a person remained outside the fold of Islam.
"I believe in Allah, in His Angels, His Scriptures, His Prophets, the Day of Judgement, and in the fact that every thing good or bad (in the world) is pre-destined by Allah the Exalted, and in the resurrection after death."
In summary the Muslims believe in Allah, in His Angels, Holy Scriptures (Quran, true bible and Torah etc.), the Prophets, believe in the life after death, including interrogation in the grave, punishment in the grave, Distraction of this Universe one day (doom day) resurrection, the Day of Judgement, rendering account of ones deeds, and passing over the Siraat Bridge, believe in the existence of Paradise, and the believers will live in it for ever, believe in the existence of Hell, with its severest punishments, and that it will last for ever. All the seven things stated in Iman Mufassal are quite evident from the sacred text of the Holy Qur'an, as well as, from the holy words of The Holy Prophet Muhammad (Peace be on him).
FIVE (5) PILLARS OF ISLAM:
The Prophet (Peace be on him) has described five fundamentals article (pillars) of Islam.
Which are (1) Believe in oneness of Allah (2) Five time daily Salaat (3) Payment of Zakat poor due (4) Fasting in month of Ramadhan (5) Hajj ( pilgrimage to Mecca).
The five (5) fundamental pillar of Islam do not include: belief in angels; the Divine Scriptures; the Day of Judgement and Fate (Taqdir) etc. The simple explanation is that the five pillars of Islam are supported by the Holy Quran and saying of the Holy Prophet Muhammad (Peace be on him). Therefore believing in them (7 essential Iman Mufassal) a muslim is obliged to believing in their saying i.e. Holy Prophet and Holy Quran.
Believes in the seven (7) essentials of Iman Mufassal from the core of his heart, and also affirms these to be true with his tongue but fails in performing the prayers; giving the Alms (Zakaat); observing the Fasts; not going for the holy pilgrimage (Hajj) remain a Muslim, but a big sinner, and disobedient to Allah. A person of this description is called Faasiq (transgressor). Such a person will be taken into task and might get salvation after undergoing punishment for the sins.
THE BELIEFS OF MUSLIMS REGARDING ALLAH:
Muslims should have the belief about Allah:
Allah the Most Exalted is One.
None is worthy of worship and devotion except Allah.
There is no partner of Allah.
He Knows everything; nothing is hidden from Him
He is All Powerful and Mighty.
It is He who created the earth, the sky, the moon, the sun, the stars, the angels, human beings, genies and the entire universe.
He gives life and death. In other words, life and death of all creatures take place by His command.
He feeds all His creation.
He does not eat, drink, or sleep.
He is Self-existent from eternity and will last till eternity.
No one has created Him.
He has no father, no son, no daughter, no wife, or other relations. He is above all such relationships.
All depend on Him. He does not depend on anyone, and He has no needs.
He is Peerless. There is nothing like Him. Nothing resembles Him.
He is free from all imperfections.
Unlike His creatures, He does not have hands, legs, nose, ears, face and shape.
After creating the angels He has appointed them to carry out specific tasks, and to manage the affairs of the universe.
He sent messengers for the guidance of His creatures; to teach people how to follow the true religion, do good deeds, and forbid them from the evil things.
THE ANGELS (MALAAIKAH):
Angels are a creation of Allah, the Almighty, created from light (NUR). They are invisible to us. They are neither male nor female. They do not disobey Allah and do not commit acts of sin. They are always busy in doing their task, assigned to them by Allah. The angels are many . No one except Allah know their exact number. We, however, know that there are many angels. Four of them are very famous and close to Allah. The first one of them is Angle Jibra'il (Gabriel) who brought Allah's Scriptures, Messages, and Commands to the prophets. The second is Angle Israfil who will blow the trumpet on the Day of Judgement. The third is Angle Mika'il who is appointed to manage the rains and to deliver livelihood to Allah's creatures. The fourth is Angle Izra'il, responsible for ending the life of Allah's creatures.
THE BOOKS OF ALLAH (The Divine Scriptures):
The Divine Scriptures (Books of Allah) are big and small. They were revealed to the Prophets. The big ones are called the Books, and the small ones are known as the Scrolls (Sahifas). The four famous Divine Books, and who are the Prophets upon whom these were revealed?
The Holy Taurat (Torah) was revealed to Prophet Musa (Moses) (Peace be upon him).
The Holy Zabur (Psalms) was revealed to Prophet Da'ud (David) (Peace be upon him).
The Holy Injil (The New Testament) was revealed to Prophet Isa (Jesus) (Peace be upon him), and the;
The Holy Qur'an, was revealed to our Holy Prophet Prophet Muhammad (Peace be upon him).
The exact number of the Divine Scrolls (Sahifas) is not known. Nevertheless, some of them were revealed to Prophet Adam (Peace be on him), some to Prophet Sheeth (Peace be on him) and some to Prophet Ibrahim (Abraham), peace be on him. Apart from theses there are other Scrolls that were revealed to some other prophets.
THE MESSENGERS OF ALLAH (peace be on them):
The Allah's Messengers (Rasuls) are human beings, and Allah's servants. Allah appointed them to convey His messages to the other human beings. They were truthful; never lie, and did not commit sin. They showed miracles on Allah's commands; convey His messages in full, without adding, or leaving out anything from the orders of Allah. Nor did they withhold any of His messages. The Prophets (Nabi) were also human beings, and Allah's servants, They convey the commands of Allah to His beings; were truthful and never told a lie, nor committed any sins. They did not subtract or add anything in the commands of Allah, nor did they hide any Divine orders.
There is a minor difference between a Messenger (Rasul), and a Prophet (Nabi). A Rasul is that Messenger, who is given a new Shariat (Divine Law) and a new Book. All Messengers are also known as Prophets, whether or not they are given a new Shariat (Divine Law). Thus, a Nabi may followed the previous Shariat and the Book. The prophet were appointed only by Allah's choice; meaning that there were no role for human effort, or intentions in this regard. This bestow, solely, depends on Allah's will. Many Messengers and Prophets came to this world only Allah knows their exact number. A Muslim should believe and testify that all of them were true and right Messengers of Allah. The first Prophet was Prophet Adam (Peace be on him)., The last Prophet was The Holy Prophet Muhammad Mustafa (Peace be on him). The Muslims believe that the appointment of the Prophets and Messengers ended with The Holy Prophet Muhammad Mustafa (Peace be on him). No new Prophet will come until the Day of Judgement. After Prophet Muhammad (Peace be on him), whosoever claims to be a prophet, is a liar. Prophet Muhammad (Peace be on him) is the most exalted and glorious of all the Messengers and Prophets. He, too, is Allah's servant and obedient to Him. He is the most exalted after Allah, the Almighty.
THE DAY OF JUDGEMENT:
The most single certain and uncertain event in this world is related to the death, everyone certain that he or she will die one day but they are not certain when they will die. It is a fundamental belief of a Muslim that one day this universe will perish on the day of Qiyamma (Doomed day) when Angel Isra'fil (Peace be on him) will blow the trumpet. Its sound will be so frightening and intense that it's shock will kill every living thing and every material will be shattered and destroyed. That day all human beings and living souls Shall die; the entire universe will perish. Mountains will fly like cotton flakes, and the planets and stars etc. will disintegrate and fall down. The Day of Judgement (Qiyamat) is about to come. But no one known its exact time. except Allah. All that is we known is that it will be on (a) Friday, the 10th of Muharram. Our Holy Prophet Muhammad (Peace be on him) has foretold some signs of Qiyamat. By observing those signs, nearness of the Day of Judgement can be determined. they are:
Sins begin to increase in the world.
People begin to disobey their parents, and become harsh towards them.
There is breach of trust.
Singing, dancing, and revelry is in abundance
The new generation begins to find fault in their forefathers.
Uneducated, and the ill-educated become the leaders.
Shepherds etc. and lowly placed people begin to build lofty buildings.
Incompetent and unworthy persons are appointed to high positions.
When the above things happen, take that the Qiyamat is near.
THE FATE (TAQDIR):
Allah knows the good and bad of every thing, and He has full knowledge of His creation even before He brings them into existence. This prior knowledge of Allah is known as Fate or Destiny. Nothing good or bad is beyond Allah's knowledge.
RESURRECTION AFTER DEATH:
The On the Day of Judgement Angel Israfil (Peace be on him) will blow the trumpet for the second time when all things would re-emerge. The human beings, too, will come to life and presented before Allah, the Almighty, in the Plain of Resurrection (Maidan-e-Hashr). All shall be called to account, and good and bad deeds Will be paid for. The day when all this takes place is called 'Day of Reckoning' (You-mul-Hashr) i.e. when all are gathered; 'Yau-mul-Jaza' i.e. the Day to repay and 'Yau-mul-Hissab' i.e. the Day of Reckoning.