All of the major books of the Ash'arites discuss the created nature of the universe through Aristotle's substance and accident (jawhar and 'arad) and also adopt the "Atomism" theory of some of the Greek Philosophers. It actually constitutes a fundamental and crucial aspect of their theology. By way of example, it is found discussed in the following:

• The books of al-Baqillani, "at-Tamheed" and "al-Insaaf"
• The book of Abdul-Qahir (Abu Mansur) al-Baghdadi (d. 429H), "Usool ud-Deen"
• "al-Farq Bayn al-Firaq" of Abdul Qahir (Abu Mansur) al-Baghdadi
• "al-Ghunyah Fee Usool ud-Deen" of Abu Sa'd an-Neesabooree (d. 478H)
• "ash-Shaamil Fee Usool ud-Deen"
• "al-Irshaad"
• "Lum' al-Adillah" of Abdul Malik al-Juwaynee (d. 478H)
• "al-Iqtisad fil-I'tiqaad" of al-Ghazali
• "Nihayat ul-Aqdaam" of ash-Shahrastani
• "al-Arba'een fee Usool ud-Deen" of ar-Raazee
• "Asaas ut-Taqdees" of ar-Raazee
• "Ma'aalim Usool ud-Deen" of ar-Raazee
• "al-Mawaaqif" of al-Eejee

We have already quoted in a previous article from al-Baqillani, his saying in his book at-Tamheed:

Chapter: The Types Of Muhdathaat (Non-Eternal, Temporal, Created Things)

And all of the muhdathaat divide into three categories: A jism (body) made up (of individual atoms), the individual atom (jawhar), and the non-essential incidental attribute ('arad) that is present with bodies (ajsaam) and substances (jawaahir)...

Abdul-Malik al-Juwaynee said in ash-Shaamil fee Usool ud-Deen (p.143):

The Islamics are all agreed that in their divisibility, bodies (al-ajsaam) end up as individual ([indivisible] parts)... and this is what the erudite amongst the geometricians have tended to, they call an indivisible part to be a point (in space) and they declared definitively that a point does not divide further.

And Abdul-Qahir al-Baghdadi says in al-Farq Bayn al-Firaq (p.315):

And they [the Ash'aris] are agreed that the components of the universe are of two types: jawaahir (substances, meaning atoms) and a'raad (accidents, unessential attributes) ...

And Abu Sa'd an-Neesabooree says in al-Ghunyah Fee Usool ud-Deen (p.49-50):

The "universe" is: a noun for every existing thing except for Allaah - the Most High - and it is divided into two types: jawaahir (substances, meaning atoms) [and] a'raad (accidents, unessential attributes)...

Ar-Raazee said in Ma'aalim Usool ud-Deen (p.32):

Speaking with al-Jawhar al-Fard (Atomism) is true...

These are just some examples.

The Ash'aris held that knowing Allaah can only be perfected through rational evidence, and deemed observation and deduction of evidence to be obligatory upon everyone. In this, they simply followed the Mu'tazilah before them, whose method they took and refined somewhat.

The Ash'aris said that it was obligatory upon everyone to know and understand the intellectual demonstration of the created and temporal nature of the universe through the notion of al-jawhar wal-'arad (substance and accident) which in turn proves the existence of a creator.

However, the use of al-jawhar wal-'arad and the Atomism theory did not just stop there. Some of the contemporary Ash'arites have attempted to defend the use of their scholars of al-jawhar wal-'arad and Atomism, claiming that though this is not found in the Book and the Sunnah, it is a general intellectual proof that all religious factions (Christians, Jews etc.) use to demonstrate the existence of a Creator and that's all the Ash'aris used it for.

And this is plainly false because it's not all that they used it for. It influenced them in other areas of creed, especially in relation to Allaah's Attributes and those actions of His tied to His Will. This will be covered in other articles inshaa'Allaah.

Source: The source of the quotes above were from Muneef al-Utaybee's "The Effect Of The Mu'tazili Thought Upon The Ash'arite Creed, Presentation and Criticism".

Note: The Greek Philosophers differed on the notion of all reality being made up of individual atoms, and Aristotle opposed this view. This was an area of long debate and discussion between them. The Ash'arites have adopted Aristotle's substance and accident (al-jawhar wal-'arad), and in addition to that they also adopted and developed further the idea of Atomism that some of the earlier Greek and Hindu Philosophers spoke of, it becoming the basic premise upon which many of their positions in the affairs of creed (Allaah's attributes, Allaah's actions, al-Qadr etc.) were built upon.