This research focuses on a topic of great significance in the life of a Muslim individual, which is the knowledge of Allah and religion according to Imam Ali (Peace be upon him) in Nahj al-Balagha. Understanding Allah is the foundation of belief and affirming His messengers and their message. It is the means of establishing monotheism, which is the right of Allah upon His servants. Knowledge of Allah instills tranquility and contentment in the hearts, leads to submission and devotion to Him, and brings forth love, reverence, and fear of Allah. Additionally, it necessitates living a righteous life and attaining eternal happiness. Those who know Allah during prosperity will continue to recognize Him during adversity and express gratitude during ease. Therefore, Imam Ali (Peace be upon him) has been chosen for this study due to his profound knowledge, understanding, jurisprudence, eloquence, and superior expertise in interpreting the noble Quran. All of these distinguished traits in his personality are firmly grounded in his understanding of Allah and religion. Thus, this humble study sheds light on the insights of this remarkable personality concerning knowledge, which is a fundamental and vital aspect in matters of faith and religions. It aims to explore the sources, limits, and levels of knowledge in this context.