Is Islamic creed a theoretical or practical methodology, what are the books and curricula for learning and applying it in reality, does abandoning some pillars of Islam constitute a defect in it, and do Muslims today need to learn it according to the methodology of the Companions?

The Islamic creed is a practical methodology that necessitates faith by verbal affirmation, conviction in the heart, and actions by the limbs and pillars. Faith increases with obedience and decreases with disobedience. Among the most prominent accredited books on creed are the Qur'an and Sunnah, in addition to books such as "As-Sunnah" by Abdullah ibn Ahmad ibn Hanbal and "Al-Aqidah Al-Wasitiyyah" by Ibn Taymiyyah. The correct creed is learned through direct reception from scholars or by referring to their explanations and writings, and then disseminating it and inviting to it with wisdom and good counsel.