In Arabic, the word jihad means striving and expending one’s energy.
In Islamic terminology, jihad means the Muslim striving to make the word of Allaah supreme and to establish His religion on earth.
The purpose of jihad in Islam is not to kill non-Muslims, rather the purpose is to establish the religion of Allaah on earth, to establish the rule of His sharee’ah, and to bring people forth from the worship of other people to the worship of the Lord of all people, from the injustice of other religions to the justice of Islam. Allaah says (interpretation of the meaning):
“And fight them until there is no more Fitnah (disbelief and polytheism, i.e. worshipping others besides Allaah), and the religion (worship) will all be for Allaah Alone”
Shaykh ‘Abd al-Rahmaan al-Sa’di said in his commentary on this verse:
Here Allaah states the purpose behind fighting for His sake, which is not to shed the blood of the kaafirs and take their wealth; rather the purpose is so that all religion (worship) will be for Allaah alone, and the religion of Allaah will prevail over all other religions, and everything that goes against that, whether it is shirk or anything else – which is what is meant by fitnah – will be repelled. If this purpose is achieved, there will be no killing or fighting.
Tafseer Ibn Sa’di, p., 98
The kuffaar whom we fight will themselves benefit from jihad. We strive against them and fight them so that they will enter the religion of Allaah which is acceptable to Him, which will lead to their salvation in this world and in the Hereafter. Allaah says (interpretation of the meaning):
“You (true believers in Islamic Monotheism, and real followers of Prophet Muhammad and his Sunnah) are the best of peoples ever raised up for mankind; you enjoin Al-Ma‘roof (i.e. Islamic Monotheism and all that Islam has ordained) and forbid Al‑Munkar (polytheism, disbelief and all that Islam has forbidden), and you believe in Allaah”
[Aal ‘Imraan 3:110]
al-Bukhaari (4557) narrated that Abu Hurayrah (may Allaah be pleased with him) said: “ ‘You are the best of peoples ever raised up for mankind’ means: the best of people for people, you bring them with chains around their necks until they enter Islam.”
Ibn al-Jawzi said: What this means is that they captured (in war) and chained as prisoners, but when they come to know the truth of Islam, they enter it willingly and will thus enter Paradise.
In the answer to question no. 20214 we have mentioned the types of jihad, of which there are four: jihad al-nafs (striving against one’s nafs or self); jihad al-shaytaan (striving against the Shaytaan); jihad al-kuffaar (striving against the disbelievers); and jihad al-munaafiqeen (striving against the hypocrites).
In the answer to question no. 34647 we have stated the wisdom behind jihad; please read this as it will answer your question.
And Allaah knows best.