Six Pillars of Iman

The First Pillar
Belief in Allah Most High

It is the foundation of the Islamic personality.
It is a basic human need, more basic than the need for his provision and sustenance.
Acts of worship only become real and valid with the feeling and awareness of their Object.
supplication
love
humility
fear
hope/reliance
adoration
Differences between the Creator and His creation.
He is free of any need for others.
He is the sole Creator of all that which pleases Him (and that which doesn't).
Allah has ordered His creation and forbidden them only in ways which are in their best interest.
He sent the Messengers and the books with the truth Ilm-ul-Ghaib.
He alone can guide to Iman. This is why the people of paradise will say:
[All praise be to Allah who guided us to this, for we never would have been guided to it if He had not guided us to it.]
The best worship is insufficient as gratitude for his bounties and mercies - they always fall short and we are need of His forgiveness.
No one's works will merit paradise. There is no contradiction between the Hadith:
None shall enter Paradise by his actions. and the verse which says:
[These are the people of paradise, therein forever, a reward for that which they used to do.]
Every human needs Allah's forgiveness of his sins.

The Second Pillar
Belief in the Angels.
Belief that among Allah's creation are angels.
Real beings, not illusions or figments of human imagination.
Created from light.
A Muslim must believe specifically in all the angels named and/or described in the Qur'an and the Sunnah.
Jibreel: in charge of delivering revelation.
Mika'il: in charge of bringing the rain.
Israfil: the blower of the horn on Qiyamah.
Malik-ul-Maut: the Angel of Death who takes people's souls at death.
The Noble Recorders: those who record people's actions.
The Protectors (Al-Mu'aqqibat): who keep people from death until its decreed time.
Ridhwan: in charge of Paradise.
Malik: in charge of Hell.
Munkar and Nakir: the questioners in the grave.
The Carriers of the Throne.
Those who record the future of the foetus.
Those who enter the Haraam: 70,000 every day.
Those who move about, descending upon gatherings at which Allah and His Book are mentioned and studied.
Belief in the angels is an integral part of Iman.
[See 2/285 Al-Baqarah]
Kufr with respect to the angels is Kufr.
[See 4/136 An-Nisaa]
They are not some metaphysical force or aspect of the human psyche or self. Deviants have said such things for many centuries, and it was not a new deviation when it was being propagated in America during this century.

The Third Pillar
Belief in the Books of Allah.
General belief in the phenomenon of the sending of books.
Six specific books mentioned in the Qur'an:
As-Suhuf of Ibrahim and Musa.
Az-Zaboor given to Daud.
At-Taurat revealed to Musa.
Al-Injeel revealed to Isa.
Al-Qur'an - the final revelation.
Attributes of the Qur'an:
Flawless and untampered with:
[See 41/42 Fusilat]
The final authority over any remnants of the previous books.
[See 5/48 Al-Maidah]
A guidance and a mercy.
[See 10/37 Yunus]
The Qur'an must be followed and applied.
[See 6/155 Al-An'aam]
Hadith narrated by Ali:
The Prophet (saws) said: Verily, there will be fitan. I said: What is the way out of them, Messenger of Allah? He said: The Book of Allah; in it is news of those who came before you; news of what is to come after you; the ruling on that which is between you; it is the decisive criterion, and is not jest. Whoever leaves it among the arrogant ones will be made small by Allah; whoever seeks guidance from other than it will be sent astray by Allah. It is the mighty rope of Allah, the Wise Reminder, and the Straight Path. With it, inclinations do not deviate nor tongues become confused. Scholars are never satiated with it; it never becomes tiresome with repetition; its wonders never diminish. ... Whoever speaks by it is truthful; whoever applies it is rewarded; whoever judges by it is just; and whoever calls to it is guided to a straight path.
- Narrated by At-Tirmidhi [Its chain is not strong because of two unknown narrators.]

The Fourth Pillar
Belief in the prophets, prayers and salutations of Allah be upon them.
Belief in the process of prophethood.
Allah in His wisdom did not neglect His creation.
Prophets sent to guide us in this life and the next.
Specific belief in the 25 prophets named in the Qur'an: (1)Adam, (2)Nuh, (3)Idris, (4)Saleh, (5)Ibrahim, (6)Hud, (7)Lut, (8)Yunus, (9)Isma'il, (10)Is-haq, (11)Ya'qub, (12)Yusuf, (13)Ayub, (14)Shu'aib, (15)Musa, (16)Harun, (17)Alyas', (18)Dhu Al-Kifl, (19)Daud, (20)Zakariya, (21)Sulaiman, (22)Ilyas, (23)Yahya, (24)Isa, and (25)Muhammad, prayers and salutations of Allah be upon him and upon all the messengers of Allah.
General belief that there are many other prophets and messengers, but never assuming anything without knowledge from Allah.
The subject matter of the prophethood.
Warnings and glad tidings.
So the disobedient will have no excuse before Allah. (Prophets sent to every nation.)
Enjoining the worship of Allah and the avoidance of At-Taghoot (Shaitaan, etc.)
[Study: 4/165, An-Nisaa; 16/36, An-Nahl]
Prophets are the best of the Awliyaa (Allies) of Allah.
What is wilaya; what it isn't.
Wilaya, Iman, Kufr and Nifaaq are all variable attributes which can all be present to varying degrees.
The best of Allah allies are the prophets (a.s.).
The best among the prophets are the messengers.
The best among the messengers are the five firmly intentioned mentioned in the Qur'an.
[See: 42/13, Ash-Shuraa]
The best of the firmly intentioned is Muhammad (saws).
Attributes of the Prophet Muhammad:
Seal of the prophets; Imam of the pious; Foremost among the sons of Adam; Imam and Khatib of the prophets when they assembled; Possessor of the Praiseworthy Position which all of mankind will wish they had attained (and which is mentioned in the Du'a of hearing the adhan); Owner of the pool in paradise; Intercessor for all mankind on the day of Qiyamah.
Allah sent him with the best of the books and the best of His law. Allah made his nation the best nation brought forth for mankind. Allah gave him (and us) all of the good that was given only partially to the previous nations. His nation is the last in creation, the first in resurrection.
From the moment of his prophethood, Allah made him the criterion (Al-Farooq) for distinguishing Allah's allies and their actions from His enemies and their actions: None can have any relationship to Allah except through belief in the Prophet (saws) and following what he brought in public and in secret. Whoever claims love or closeness to Allah while disobeying the message is actually drawing closer to Sheytan, farther from Allah.

The Fifth Pillar
Belief in the resurrection . Reconstruction of the body and return of the soul to it. People will come forth out of their graves like locusts. Faces bent down. Rushing to the Caller.
[See 53/76 Al-Qamar; 70/43 Al-Ma'arij; 17/49 Al-Israa; 36/78 Yasin; 20/108 Taha]
The resurrection is of the body and the soul, not some metaphysical resurrection of the latter.
Twelve verses from the Qur'an which prove that.
Hadith: The sun will come down toward the people on the day of Qiyamah until it is only about a mile up. The people will be in their own perspiration according to their acts: some of them will be in it up to their ankles, some up to their groin and others up to their chins, and he pointed to his mouth. Narrated by Muslim.
A disbeliever once came to the Prophet (saws) with an old bone, crumbled it with his hand and said: O Muhammad, will Allah bring this back to life after it has rotted?! The Prophet said: Yes, Allah will resurrect this and he will cause you to die, bring you back to life, and put you into the fire of Jahannam!

The Sixth Pillar
Belief In Predestination and Decree
A Muslim believes in Allah's predestination of all things and events (Qadhaa), His decree (Qadar), His wisdom in His actions, and His will. Nothing in the universe can occur, even the voluntary actions of His slaves, except after Allah's knowledge, and His decree of that event. A Muslim further believes that Allah is Just in His predestination and His decree, Wise in all of His actions. His wisdom follows His will: Whatever He wills is, and whatever He does not will is not. There is no power nor any movement except by Allah. This is substantiated by the textual and logical proofs which follow:
Textual Evidence
1) Allah informed us of this in the Qur'an:
[Verily, we have created everything in (predetermined) measure.] Qur'an 54/49
[And there is nothing whatsoever but that its reserves are with us, and we do not send it down except in known measure.] Qur'an 15/21
[No calamity strikes in the earth nor in your selves but that was in a book since before We created it (i.e. the event). That is easy for Allah.] Qur'an 57/22
[No calamity strikes except with the permission of Allah.] Qur'an 64/11
[Say: Nothing will befall us except what Allah had decreed for us, He is our protecting Ally, and upon Allah let the believers depend.] Qur'an 9/51
[And with Him are the keys of the unseen, no one knows them except Him. He knows all that is in the ocean and on the land. No leaf falls without His knowledge, nor any particle in the dark recesses of the earth, nor anything green and fresh or dry and withered but that it is in a clear book.] Qur'an 6/59
[This is nothing less than a reminder to all the worlds. * For whoever among you has an intention to go straight. * But you will never have this intention unless Allah so wills, Lord of the worlds.] Qur'an 81/27-29
[Those for whom good has already been decreed by us will be far removed from it (i.e. hell).] Qur'an 21/101
[If only, when you entered your garden, you had said: (This is only) by the will of Allah. There is no power except from Allah.] Qur'an 18/39
[Praise be to Allah who guided us to this, and we would never have attained guidance if Allah had not guided us.] Qur'an 7/43
2) The Prophet (saws), too, has informed us about the reality of Allah's predestination and decree in many hadith:
Verily, each one of you is formed in his mother's womb forty days as a drop, then he is something suspended for a similar period, then he is a piece of flesh like a chewed piece of meat for another period of forty days, then the angel is sent to insert the soul. This angel is ordered to record four things: the sustenance which he will receive during his lifetime, the length of his life, all actions that he will do, and whether he will end up miserable (in hell) or joyous (in paradise). I swear by the One other than whom there is no deity, one of you may do the works of the people of paradise right up until there is only an arm's length between him and paradise, but his destiny overtakes him, so he does the actions of the people of the fire and enters it. And, verily, one of you may do the works of the people of hell until there is nothing between them and hell except for one arm's length, but his destiny overtakes him, and so he does the works of the people of paradise, and enters it. (Muslim)
Young man, I will teach you some words: Preserve (your obligations toward) Allah and He will preserve you. Guard (your obligations toward) Allah, and you will find Him on your side. When you ask, ask Allah. When you seek aid and succour, seek it from Allah. And know, that if the entire nation got together to benefit you in some way, they could never benefit you at all except for that which Allah had already decreed for you. And, if they all got together to harm you in some way, they could do you no harm except for that which Allah had already decreed for you. The pens have been lifted, and the tablets have dried. (At-Tirmidhi, and he rated it Sahih.)
The first thing which Allah created was the pen. Then, He said to it: Write. It asked: My Lord, what should I write? He said: Write the proportions of all things up until the Hour. (Ahmad, At-Tirmidhi, and it is hassan.)
Adam disputed with Musa. Musa said to Adam: O, Adam, you are the father of the human race, Allah created you with His hand, and blew into you of His spirit, and made His angels prostrate to you, why did you expel yourself and us from the garden? Adam said to him: You are Musa whom Allah favoured with His speech, and wrote for you the Taurah with His hand, so (tell me) by how many years before my creation did you find it written about me: [... then Adam disobeyed his Lord and got lost.] (Qur'an 20:121)? Musa said: By forty years. Then, Adam said: So how do you blame me for something which Allah had decreed for me before my creation by forty years? The Prophet said: And so, Adam defeated Musa in the dispute.
Iman (faith) is to believe in Allah, His angels, His revealed books, His messengers, the last day, and the predestination of all things both (those which appear) good and (those which appear) bad. (Muslim)
Act, for each of you will find easy that for which he was created. (Muslim)
Verily, oaths do not change destiny. (Sahih)
O, Abdullah ibn Qais, should I not teach you a word which is one of the treasures of paradise? (It is to say): There is no movement nor any power except from Allah.
Someone said: That which Allah wants and you want. To which the Prophet (saws) replied: That which Allah alone wants. (An-Nasaa'i, and he rated it sahih)
3) Millions of people from the nation of Muhammad (saws) have believed in Allah's predestination and decree of all things and events including its scholars, righteous ones and others. They all believed too in His wisdom and His will and that everything is known to Allah in advance of its occurrence, and only takes place by His decree. Nothing can take place anywhere in His kingdom except for that which He wills. What He wills is, and what He does not will is not. The pen has already recorded the destinies of all things up to the establishment of the hour.

Source : http://www.missionislam.com/knowledge/sixpillarsiman.htm