Because the mission of the community is to “enjoin good and forbid evil” so that “there is no mischief and corruption” on earth, the doctrine of jihad is the logical outcome. For the early community it was a basic religious concept.
The lesser jihad, or holy striving, means an active struggle using armed force whenever necessary. Visit website TheMuslimPath
The object of such striving is not the conversion of individuals to Islam but rather the gaining of political control over the collective affairs of societies to run them in accordance with the principles of Islam. Individual conversions occur as a by-product of this process when the power structure passes into the hands of the Muslim community.
In fact, according to strict Muslim doctrine, conversions “by force” are forbidden, because after the revelation of the Qurʾān “good and evil have become distinct,” so that one may follow whichever one may prefer (Qurʾān), and it is also strictly prohibited to wage wars for the sake of acquiring worldly glory, power, and rule. With the establishment of the Muslim empire, however, the doctrine of the lesser jihad was modified by the leaders of the community.
Their main concern had become the consolidation of the empire and its administration, and thus they interpreted the teaching in a defensive rather than in an expansive sense.
The Khārijite sect, which held that “decision belongs to God alone,” insisted on continuous and relentless jihad, but its followers were virtually destroyed during the internecine wars in the 8th century.