Morteza Motahari was a prominent thinker who, alongside Islamic sciences, researched Western philosophy and by comparing them tried to respond to religious doubts and to fulfill one of his duties which was to rationally defend Islamic doctrines. To this end, he studied and criticized Western philosophical schools as far as they had been translated into Persian. One of these schools was existentialism, whose leading figure before the Islamic Revolution was the famous French philosopher Jean-Paul Sartre. Sartre was an atheist philosopher and founded his philosophy on this basis. As a religious thinker, Motahari has a critical approach to Sartre's philosophy and has rejected his views on numerous occasions. In this article, these views are categorized into eight headings, and under each heading, Sartre's position is first presented, followed by Motahari's criticism, and finally the author's evaluation. In the first part of the article (published in the previous issue of the journal), following the introduction, four headings were examined: ‘The rejection of a fixed human essence’, ‘The precedence of existence over essence in human beings’, ‘Freedom’, and ‘The incompatibility of God and human freedom’. In the second part, four headings will be addressed: ‘Nihilism’, ‘The relativity of morality’, ‘Responsibility’, and ‘Humanitarianism’. Then, under the heading "Conclusion," the root of the disagreement between these two thinkers will be pointed out.