There are six articles of Faith in Islam:

1. Belief in Allah (God),
2. Belief in His Angels,
3. Belief in His Books,
4. Belief in His Messengers,
5. Belief in the Last Day, and
6. Belief in the Divine Preordainment and Divine Decrees (Qada' and Qadar).

Belief in Allah:

This article means to believe that Allah is the only One God, to whom worship is due, that He is the Creator of everything and the Sustainer of everything, that it is He Who gives life and causes death, and that He is Unique in His Names and Attributes.

Belief in His Angels:

Allah has created the angels from light. They are honorable slaves of Allah, who obey Him and execute His Commands. Allah describes them:
"They never disobey Allah in what He commands them, and they do as they are commanded." (66:6)

Allah created them to worship Him, and only Allah knows how many they are. Among them are:
- Gabriel who is charged with delivering Divine revelations to the Prophets and Messengers of Allah,
- Michael who is charged with the rain,
- The angel of death who is charged with collecting human souls,
- The bearers of the Throne of Allah and
- The guards of Paradise and Hell.

Beside these, there are angels who guard humans, others who record people's deeds and utterances and still others who are charged with various other duties and tasks.

Belief in His Books:

Belief in His Books is believing that Allah the Exalted did reveal Books to His Messengers to convey them to their people. Those Books comprise the Speech of Allah. These were doubtlessly chaste at the point of revelation, and whenever a Book or Scripture was revealed, it abrogated the preceding one. The known Divine Scriptures are:
1. The Torah, the Book Allah revealed to Moses (peace be upon him).
2. The Psalms, the Book revealed to David (peace be upon him).
3. The Gospel, revealed to Jesus (peace be upon him).

The Books in the hands of the Christians and Jews today, that is, the Torah and the Bible with the Old Testament and the New Testament are not authentic because they have been distorted, altered and tampered with. Moreover, they were abrogated by the last of Allah's Books, the Qur'an.

Belief in His Messengers:

Muslims attest that Allah did send Messengers to every nation inviting them to worship Him Alone. This belief entails, too, denouncing all gods that are worshipped besides Allah or instead of Him, and that all Messengers were truthful and discharged their duty in the best manner. Allah sent many Messengers, and only Allah knows how many. It is incumbent upon all Muslims to believe in all the Prophets and Messengers. He who denies one of them denies all. The first Messenger Allah sent to mankind was Noah, and the last was Muhammad. Allah says: "And We have sent a Messenger to every people preaching: Worship Allah, and shun the Taghut (deities worshiped besides or other than Allah)." (16:36)

All Prophets and Messengers were human beings. Allah distinguished them by commissioning them as Prophets and Messengers and supported them with miracles. They had no Divine qualities, and had no access to the Unseen world. But Allah sent Muhammad to all mankind saying:
"Say (O Muhammad): 'O mankind, I am the Messenger of Allah to you all....'" (7:158)

Of all the Messengers, there are five who were the most persevering and determined to do what Allah had enjoined them. They were Noah, Abraham, Moses, Jesus and Muhammad (SAWS), who was the last and the best of them all and remains the best of all human beings.

Belief in the Last Day:

Muslims attest to the truth of everything Allah or His Messenger (SAWS) said about death. Allah has not created His creations in vain. He created men and jinn to worship Him and promised Paradise as a reward to those who obey Him and His Messengers, and Hell-fire to those who disobey Him or His Messengers. He has set a certain period for the whole universe, whose end will be the Final Hour. During the Final Hour, humans will be questioned about their deeds in this world. Those deeds will be weighed for them. The one whose good deeds overweigh his evil deeds will prosper. The one whose bad deeds outweigh his good ones will be condemned to Hell-fire. Islam is a precondition for the acceptance of any good deed.

The Description of Paradise:

Paradise, Jannah in Arabic, is the abode that Allah has prepared for believers. It holds means of everlasting bliss no eye has seen, no ear heard or human imagined. In it are pure female mates, rivers of milk, rivers of wine, rivers of pure honey and every kind of delicious fruit and meat. Its residents will not experience exhaustion, boredom or death.

The Description of Hell:

Hell-fire is the abode Allah has prepared for infidels who deny Him and His Messengers. Its food is intolerantly bitter, and its drink is the pus exuding from the skins of its inmates. Its depth is unfathomable. Infidels and the hypocrites will live in it forever.

Belief in the Divine Preordainment and Divine Decrees (Qada' and Qadar):

Doom (Qada') is the general Decree of Allah that every human shall die, whereas a Divine Decree (Qadar) is a particular Decree of Allah or the execution of Qada', that certain person is to die at a particular time and place. Hence believing in this article entails believing that Allah has created everything and has foreordained its proper measure.

The Facets of Qadar:

1. Allah is well acquainted with everything taking place, and His Knowledge encompasses everything.
2. Allah has pre-assigned portions of everything in the Preserved Tablet.
3. Nothing takes place in the heavens or on the earth without the Will of Allah and His Wish. Whatever Allah wills, takes place and whatever He does not will, does not take place.
4. Allah is the Creator of all things. There is no other creator beside Him.

Summarized from: A Brief Look Upon Islam