Why did Mecca's leaders try to prevent the spread of Muhammad's message

Mecca leaders were worried about losing their political and economic power. The expansion of Islam, the new religion preached by Muhammad, contradicted traditional beliefs and practices of the Arab tribes. Its condemnation of idolatry and its monotheistic character was particularly troubling for them. The Quraysh tribe heads in Mecca controlled the Kaaba - a key religious place still important in Islam -, and their political and religious power rested upon managing access to polytheistic shrines. So, Muhammad's doctrine of one God - Allah - questioned their legitimacy and sociopolitical position.