From the most imperative of a Muslim's knowledge is that he understands & implements the six articles of faith as described in the Qurʾān & Sunnah. This article will give a brief overview of them all, ʾIn shāʾ Allāh:
Belief in Allāh (عز و جل) encompasses worshipping Him alone, without associating any partners with him, and rejecting polytheism. Worship of Allāh (عز و جل) consists of offering the 5 daily prayers every day, making dhikr to Him (عز و جل), etc.
Belief in the Angels encompasses acknowledging their existence and understanding each of their due purposes. Allāh (عز و جل) has appointed several angels for different purposes, such as bringing down the revelation to the messengers. They are consistently obedient to Allāh (عز و جل) and they do not commit any sins.
Belief in the Messengers encompasses implementing the lessons learned from the stories of each of His (عز و جل)'s messengers, and implementing the Sunnah of the final Prophet, Muḥammad (ﷺ). Rejection of the Sunnah is considered disbelief and one is not considered a believer if he rejects the Qurʾān and/or Sunnah.
Belief in the Books encompasses implementing the sayings that are brought down upon us via His (عز و جل)'s Book, the Qurʾān, as well as the Sunnah of the Prophet (ﷺ). It is incumbent upon a Muslim to implement all that is told in these revelations.
Belief in the Last Day encompasses acknowledging the existence and inevitable upcoming of the Day of Resurrection, the day when we will all be brought together with our deeds.
Belief in the Divine Decree (Qadr) encompasses acknowledging that all actions are created by Allāh (عز و جل). The Qadr has already been written in al-Lawh al-Mahfūz (the preserved tablet), so the Muslim accepts that everything that occurs to him was from His Lord (عز و جل), thus he is pleased with it, and submits to it.
The Prophet (ﷺ) said:
"(The matter of the Creation of) a human being is put together in the womb of the mother in forty days, and then he becomes a clot of thick blood for a similar period, and then a piece of flesh for a similar period. Then Allāh sends an angel who is ordered to write four things. He is ordered to write down his (the new creature's) deeds, his livelihood, his (date of) death, and whether he will be blessed or wretched (in religion). Then the soul is breathed into him. So, a man amongst you may do (good deeds till there is only a cubit between him and Paradise and then what has been written for him decides his behavior and he starts doing (evil) deeds characteristic of the people of the (Hell) Fire. And similarly a man amongst you may do (evil) deeds till there is only a cubit between him and the (Hell) Fire, and then what has been written for him decides his behavior, and he starts doing deeds characteristic of the people of Paradise." (1)
And Allāh (ﷻ) knows best.
May Allāh bless you, and shukran.
Sources :
Narrated ʿUmar (رضي الله عنه): "We were sitting with the Prophet (ﷺ) when a man came to him whose clothes were intensely white and whose hair was intensely black; no signs of travel could be seen upon him, and none of us recognized him. He sat down facing the Prophet (ﷺ), with his knees touching his, and he put his hands on his thighs, and said: 'O Muhammad, what is Islam?' He said: 'To testify that none has the right to be worshipped but Allāh, and that I am the Messenger of Allāh, to establish regular prayer, to pay Zakat, to fast in Ramadān, and to perform Hajj to the House (the Ka'bah).' He said: 'You have spoken the truth.' We were amazed by him: He asked a question, then told him that he had spoken the truth. Then he said: 'O Muhammad, what is Iman (faith)? He said: 'To believe in Allāh, His angels, His Messengers, His books, the Last day, and the Divine Decree (Qadr), both the good of it and the bad of it.' He said: 'You have spoken the truth.' We were amazed by him. He asked a question, then told him that he had spoken the truth. Then he said: 'O Muhammad, what is Ihsan (right action, goodness, sincerity)? He said: 'To worship Allāh as if you see Him, for even though you do not see Him, He sees you.' He asked: 'When will the Hour be?' He said: 'The one who is being asked about it does not know more than the one who is asking.' He asked: 'Then what are its signs?' He said: 'When the slave woman gives birth to her mistress' (Wakīʿ said: This means when non-Arabs will give birth to Arabs') 'and when you see barefoot, naked, destitute shepherds competing in constructing tall buildings.' The Prophet (ﷺ) met me three days later and asked me: 'Do you know who that man was?' I said: 'Allāh and his Messenger know best.' He said: 'That was Jibril, who came to you to teach you your religion.'" (Sunan ibn Mājah 63, graded Ṣaḥīḥ)
1. Ṣaḥīḥ al-Bukhārī 3208, also reported in Muslim