What is Islamic religious knowledge (Al-Ilm Al-Shari) linguistically and terminologically?

Sacred knowledge (al-ʿilm al-sharʿī) is the knowledge that serves the Sacred Law (Sharīʿah). It includes what is sought for its own sake, such as the sciences of the Qur’an, Sunnah, Fiqh (jurisprudence), Tawḥīd (monotheism), and Sīrah (Prophetic biography), as well as what falls under the category of means, such as auxiliary sciences like language, grammar, uṣūl (principles), and rhetoric.

It is divided into: - Individual obligation (farḍ ʿayn): This is what an individual responsible (mukallaf) for an obligatory act cannot fulfill without, such as the manner of ablution (wuḍūʾ) and prayer (ṣalāh), and knowing the diseases of the heart for one whose heart is not free from them. - Communal obligation (farḍ kifāyah): This is what people cannot do without for the establishment of their religion, such as memorizing the Qur’an and Hadith and their sciences, and the sciences of Fiqh, uṣūl, and language; or what is needed for the sustenance of worldly affairs, such as medicine, accounting, and crafts. - Recommended (mandūb): This is the expansion in sacred sciences and their tools, and the exploration of their intricacies.