I have already posted the orthodox Sufi opinion on jihad.
Ibn Abi Zayd al-Qayrawani (d. 996), Maliki jurist 1
Jihad is a precept of Divine institution. Its performance by certain individuals may dispense others from it. We Malikis [one of the four schools of Muslim jurisprudence] maintain that it is preferable not to begin hostilities with the enemy before having invited the latter to embrace the religion of Allah except where the enemy attacks first. They have the alternative of either converting to Islam or paying the poll tax (jizya), short of which war will be declared against them.
Ibn Taymiyya (d. 1328), Hanbali jurist 2
Since lawful warfare is essentially jihad and since its aim is that the religion is God’s entirely and God’s word is uppermost, therefore according to all Muslims, those who stand in the way of this aim must be fought. As for those who cannot offer resistance or cannot fight, such as women, children, monks, old people, the blind, handicapped and their likes, they shall not be killed unless they actually fight with words (e.g. by propaganda) and acts (e.g. by spying or otherwise assisting in the warfare).
From (primarily) the Hanafi school (as given in the Hidayah) 3
It is not lawful to make war upon any people who have never before been called to the faith, without previously requiring them to embrace it, because the Prophet so instructed his commanders, directing them to call the infidels to the faith, and also because the people will hence perceive that they are attacked for the sake of religion, and not for the sake of taking their property, or making slaves of their children, and on this consideration it is possible that they may be induced to agree to the call, in order to save themselves from the troubles of war… If the infidels, upon receiving the call, neither consent to it nor agree to pay capitation tax, it is then incumbent on the Muslims to call upon God for assistance, and to make war upon them, because God is the assistant of those who serve Him, and the destroyer of His enemies, the infidels, and it is necessary to implore His aid upon every occasion; the Prophet, moreover, commands us so to do.
al-Mawardi (d. 1058 ), Shafi’i jurist 4
The mushrikun [infidels] of Dar al-Harb (the arena of battle) are of two types: First, those whom the call of Islam has reached, but they have refused it and have taken up arms. The amir of the army has the option of fighting them…in accordance with what he judges to be in the best interest of the Muslims and most harmful to the mushrikun… Second, those whom the invitation to Islam has not reached, although such persons are few nowadays since Allah has made manifest the call of his Messenger…t is forbidden to…begin an attack before explaining the invitation to Islam to them, informing them of the miracles of the Prophet and making plain the proofs so as to encourage acceptance on their part; if they still refuse to accept after this, war is waged against them and they are treated as those whom the call has reached….
In Khaldun (d. 1406), jurist (Maliki), renowned philosopher, historian, and sociologist, summarized these consensus opinions from five centuries of prior Muslim jurisprudence with regard to the uniquely Islamic institution of jihad:
In the Muslim community, the holy war is a religious duty, because of the universalism of the [Muslim] mission and [the obligation to] convert everybody to Islam either by persuasion or by force...The other religious groups did not have a universal mission, and the holy war was not a religious duty for them, save only for purposes of defense...Islam is under obligation to gain power over other nations.