"Say! O disbelievers! I worship not that which you worship; Nor worship you that which I worship; And I shall not worship that which you worship. Nor will you worship that which I worship. Unto to you your religion, and unto me my religion."

[The Holy Quran Surah al-Kafirun, Chapter 109 and Verses 1-6]

During the Makkah period of Islam, there was no mutual fighting which took place between the Muslims and the disbelievers. It was a one sided attack which was declared by the disbelievers against the Muslims, and they persecuted many Muslims and killed some of them. The Muslims were weak militarily, in terms of manpower and logistics. However, after the Hijrah to Medinah, the situation changed. We can learn this from the kind of Revelation, which Allah, revealed in Makkah, in which He instructed the Muslims to leave the disbelievers alone, and not to engage in a losing battle with them.