Then comes the mention of belief in the Angels and Messengers because they are the mediators between Allāh and His creation regarding the conveyance of His messages. Thus, the Angels descend with the revelation (from Allāh) and bring it to the Messengers and the Messengers convey it to the people.

There is wisdom behind – and Allāh knows best- the arrangement of the pillars of Īmān in the verses of the Qurʾān and the aḥādīth, although the waaw (و) doesn’t exactly necessitate arrangement:

The pillars of Īmān have begun with belief in Allāh because it is absolutely the foundation and (all) the other pillars aside from it come in succession to it.

Then comes the mention of belief in the Angels and Messengers because they are the mediators between Allāh and His creation regarding the conveyance of His messages. Thus, the Angels descend with the revelation (from Allāh) and bring it to the Messengers and the Messengers convey it to the people. The Most High says,

يُنَزِّلُ الْمَلَائِكَةَ بِالرُّوحِ مِنْ أَمْرِهِ عَلَىٰ مَن يَشَاءُ مِنْ عِبَادِهِ أَنْ أَنذِرُوا أَنَّهُ لَا إِلَـٰهَ إِلَّا أَنَا فَاتَّقُونِ

“He sends down the Angels with inspiration of His Command to whom of His slaves He pleases (saying): ‘Warn mankind that none has the right to be worshipped in truth except I, so fear Me.”
[Sūrah al-al-Naḥl 16:2]

Thereafter is mention of belief in the books because they are the criterion and returning point that which the Prophets and Messengers, ʿalayhim as-ṣalātu was-salām, came with by way of the Angels from Allāh the Most High, in order to judge between the people in that which they differ. The Most High says,

فَبَعَثَ اللَّـهُ النَّبِيِّينَ مُبَشِّرِينَ وَمُنذِرِينَ وَأَنزَلَ مَعَهُمُ الْكِتَابَ بِالْحَقِّ لِيَحْكُمَ بَيْنَ النَّاسِ

فِيمَا اخْتَلَفُوا فِيهِ

“… Allāh sent Prophets with glad tidings and warnings, and with them He sent the Scripture in truth to judge between people in matters wherein they differ.”
 [Sūrah al-Baqarah 2:213]

Afterwards is mention of belief in the Last Day as it is the appointment of recompense for (all of) the actions which is the outcome and fruits behind belief in Allāh, His Angels, His books and His Messengers or the denial of them. For that reason, from the adequacy of the Divine Justice (of Allāh) is the establishment of this Day to judge between the oppressor and the oppressed and the establishment of ‘adl (equity) between the people.

Lastly is the mention of belief in the Qadā’ and Qadr due to its extreme importance in driving the believer towards the performance of righteous actions and adopting the proper and beneficial means (i.e. in obtaining provisions, etc.) together with reliance upon Allāh, the One free from all imperfections. In order to make evident that there isn’t any contraḍīction between the legislation of Allāh that He sent His Messengers with and revealed His books based upon and between His judgment and pre-decree. Contrary to those who erroneously believe that the innovators and polytheists say,

لَوْ شَاءَ اللَّـهُ مَا عَبَدْنَا مِن دُونِهِ مِن شَيْءٍ نَّحْنُ وَلَا آبَاؤُنَا وَلَا حَرَّمْنَا مِن دُونِهِ مِن شَيْءٍ

“…If Allāh had willed neither we nor our fathers would have worshipped aught but Him, nor would we have forbidden anything without (a command from) Him.”
[Sūrah al-al-Naḥl 16:35]

They (tried) to justify that which they were upon from disbelief (claiming) that Allāh decreed it for them. So if He decreed it for them then He must have been pleased with it from them – as they claim. So Allāh rebutted them with the fact that if He was – so called – pleased with it then He would not have sent His Messengers with the disavowal of it, as He says,

فَهَلْ عَلَى الرُّسُلِ إِلَّا الْبَلَاغُ الْمُبِينُ

“…Then! Are the Messengers charged with anything but to convey clearly the Message?”
[Sūrah al-al-Naḥl 16:35]

Source: http://www.sahab.net/home/index.php?Site=News&Show=906

Translator: Abū Fouzaan Qaasim