The Holy Quran, emphasizing the Arabian Peninsula, refers to the life of ignorance in the world parallel to the rise of Islam. Of course, this question is raised, what was the situation of Iran in the era of the rise of Islam? And the more precise question is, how was the religious status of kings as the main element of power in Iran parallel to the rise of Islam? Using a descriptive-analytical method and a historical approach, this article has answered the question of what are the characteristics and consequences of the religious life of the Sassanid kings? The output of the mentioned research emphasizes the unreasonable characteristics in the religious life of the Sassanid kings and its negative consequences. The current research is based on four indicators: the definition of God-like position, the definition of the position of "God's appointed successor", religious diversity, and aggressive approach towards other religions. The mentioned indicators led to the creation of deviation in Zoroastrian religion, wealth accumulation of Zoroastrian elders, distancing of people from spirituality and limiting themselves to harsh and unreasonable actions, expansion of Christianity in Iran, and migration of people. The stated conditions, among other things, had created a difficult situation for the people of Iran; Therefore, when Islam entered Iran, people welcomed it and became Muslims.