Rationality is a characteristic of modern-era progress in answering the problems of human life. However, why are various problems arising from various aspects today, such as environment, ecology, and spirituality?. This paper aims to unravel the phenomenon of discrepancy in the development of one's religiosity and rationality, then the author will provide a model of balance between the two according to Islamic psychology to overcome the problem. By using critical analytical descriptive methods and a qualitative approach, the research found several important findings; First, in the Islamic context, the activity of thinking is carried out by the qalb (heart) as a spiritual representation and the mind (brain) as a rational representation. Second, the tauhidic principle of Islam sees reality empirically and nonempirically. Empirical is articulated by the rational and non-empirical by the qalb. Third, the involvement of the qalb and mind in thinking will bring the human soul to a state of its nature, namely nafs muṭmainnah. Fourth, the balance between rationality and religiosity in Islam can occur simultaneously by means of consistent jihad nafs (jihad of the soul).