When studying Ghazali and similar authors, it’s important to understand the division of two types of the knowledge:
- Ilm al-Muamalah (علم المعاملة): The outward knowledge that can be taught and learned. It is the knowledge of transactions between us and Allah ﷻ, us and our hearts (ex: sincerity), us and other people (ex: being brotherly and sisterly), and us and the creation. This is the knowledge of practice, and it always involves others as well, sometimes even yourself (like observing your heart and working to silence the khawatir, the suggestions floating around your heart from various sources).
Learning fiqh and how to properly worship our Creator and get our hearts right while doing so. Getting your life right in general. This knowledge is obligatory on every individual, as it is essential to the path of the hereafter. Getting your ibadat right spiritually, in your heart, is not the job of the faqih, he only tells you the outward aspect. Scholars like Ghazali and proper, qualified shuyukh (beware of charlatans) can help you with getting your heart right.
- Ilm al-Mukashafah (علم المكاشفة): Knowledge that brings about the unveiling and lifts the cover off everything the prophet ﷺ has told you and Allah ﷻ in the Qur’an has told you. You come to know the garden is real, Hell is real, the Day of Judgement is real, and Allah ﷻ is real. You may even see the Garden in a dream or have various other sorts of unveilings. Ghazali can’t teach you ilm al-mukashafah, you have to get that for yourself. But he will teach you everything that will take you up to that. He will teach you ilm al-muamalah, the transactional knowedge. He will teach you how to get your heart right and get your tongue right, and stop talking about things that do not concern you (and worse things than that). He will teach you to avoid filthy things and filthy ideas. If you get this transactional knowledge, it will open up your heart to everything else. The essence of every human being is such that every one of us can tap into infinite knowledge in our hearts. You can know that the Garden and the Fire and the Judgement are real. These are cosmic realities. All you have to do is get your heart right, get it pure and filled with sound knowledge, and then you will open it up to the unveilings.