Final answer:
Jihad in Islam signifies a 'struggle', with Greater Jihad focusing on personal spiritual development through adhering to the Five Pillars of Islam and Lesser Jihad potentially involving collective action, including military efforts, to promote or protect Islam. However, like the Christian 'just war', an authoritative declaration is traditionally required for it to be considered a jihad.
Step-by-step explanation:
The concept of jihad in Islam is a multifaceted one, and it's important to distinguish between its various forms. The term jihad, meaning "struggle" in Arabic, encompasses both the internal struggle against sin (Greater Jihad) and the external effort to make society conform to the guidance of Allah, which can sometimes include military efforts (Lesser Jihad).
The Greater Jihad refers to the personal, spiritual effort of a Muslim to follow the religious teachings and live according to the example of the Prophet Muhammad. This includes the adherence to the Five Pillars of Islam, which are central practices of the faith: the declaration of faith (Shahadah), prayer (Salat), charitable giving (Zakat), fasting during Ramadan (Sawm), and the pilgrimage to Mecca (Hajj).
The Lesser Jihad can expand to include additional practices, dietary restrictions, and the avoidance of certain behaviors such as usury and gambling. Unlike the Greater Jihad, the Lesser Jihad can involve collective action to protect or promote Islam, which historically could entail military campaigns that were supposed to be declared by a recognized authority within the faith.
It is also crucial to note that like the concept of a "just war" in Christian theology, jihad was intended to be declared by proper authorities, and conflicts were not always labeled as jihad by Muslims, even when fought for religious reasons.