There are some ways in which we can trace Muhammad’s philosophy back to his life experiences, but in other ways, we simply cannot. Some of Muhammad’s philosophy is better explained by his spiritual experiences.
Bentley and Ziegler point out that Muhammad lived in a community in which there were both Jews and Christians. As a merchant, he dealt with people from outside his own group. These life experiences exposed him to the ideas of monotheism even though his own people were, as a rule, polytheistic. What this means is that Muhammad’s life experiences would have opened him to the possibility that there might be only one god.
However, there is no way to say that his life experiences led him to believe so strongly in that idea. Instead, we have to attribute this to his spiritual experiences. When Muhammad was visited by the archangel Gabriel, his ideas were fundamentally changed. He came to believe very strongly in the idea of monotheism and in the inherent evilness of polytheism.
Thus, we can clearly say that Muhammad’s life experiences as a merchant opened him to the possibility of monotheism, but we have to say that he came to actually believe in monotheism because of his spiritual experiences, not because of his more “regular” life experiences.