A problem arises in classical kalām: if Allah’s essence is beginningless and His attributes are also beginningless, does that multiply independent necessary divine substances?
An essence concerns the independently existing being, whereas an attribute expresses a perfection such as knowledge, power, or life belonging to that being. To affirm an attribute as eternal is not to make it a separate, self-subsistent deity.
Calling divine knowledge eternal, for example, does not mean that knowledge is another god deliberating alongside Allah. Distinguishing the plurality of attributes from a plurality of independently necessary essences is essential to understanding unity together with the affirmation of divine perfections.