It is obligatory to have belief in the following:
`Isa ibn Maryam (peace be upon him) was raised alive, in both body and soul, to the heavens. He is not yet dead; he was not killed by
the Jews nor crucified, but it appeared so to them as it was someone to them who resembled him, so the Jews claimed that they killed and crucified him.
The Christians agreed with their false claim, out of their ignorance. Allah (Exalted be He) says:
Because of their breaking the covenant, and of their rejecting the Ayât (proofs, evidence, verses, lessons, signs, revelations, etc.) of Allâh, and of their killing the Prophets unjustly, and of their saying: "Our hearts are wrapped (with coverings, i.e. we do not understand what the Messengers say)" - nay, Allâh has set a seal upon their hearts because of their disbelief, so they believe not but a little.
And because of their (Jews) disbelief and uttering against Maryam (Mary السلام عليهما) a grave false charge (that she has committed illegal sexual intercourse);
And because of their saying (in boast), "We killed Messiah ‘Isâ (Jesus), son of Maryam (Mary), the Messenger of Allâh," - but they killed him not, nor crucified him, but it appeared so to them [the resemblance of ‘Isâ (Jesus) was put over another man (and they killed that man)], and those who differ therein are full of doubts. They have no (certain) knowledge, they follow nothing but conjecture. For surely; they killed him not [i.e. ‘Isâ (Jesus), son of Maryam (Mary) عليهما السلام]:
But Allâh raised him [‘Isâ (Jesus)] up (with his body and soul) unto Himself (and he عليه السلام is in the heavens). And Allâh is Ever All-Powerful, All-Wise.
(Part No. 3; Page No. 334)
`Isa ibn Maryam is not Allah's son nor did he have a human father, or any other. Allah commanded His Angel Messenger, Jibril (Gabriel, peace be upon him) to breathe His Ruh into Maryam, and she became pregnant with `Isa (peace be upon him). Allah (Exalted be He) says:
And mention in the Book (the Qur’ân, O Muhammad صلى الله عليه وسلم the story of) Maryam (Mary), when she withdrew in seclusion from her family to a place facing east.
Allah (Exalted be He) made Jihad lawful to spread Islam, to eliminate the obstacles to Da`wah (calling to Islam), and to deter anyone who may want to assault or cause harm to the Du`ah (callers to Allah). It was to remove Fitnah (sedition) and enable security and peace to prevail, the Word of Allah to be supreme, Kufr (disbelief) to be the inferior, and people to enter in Allah's Din (religion, Islam) in crowds. Allah (Exalted be He) says:
And fight them until there is no more Fitnah (disbelief and polytheism, i.e. worshipping others besides Allâh) and the religion (worship) will all be for Allâh Alone [in the whole of the world]. But if they cease (worshipping others besides Allâh), then certainly, Allâh is All-Seer of what they do.
...and fight against the Mushrikûn (polytheists, pagans, idolaters, disbelievers in the Oneness of Allâh) collectively as they fight against you collectively. But know that Allâh is with those who are Al-Muttaqûn (the pious).
He (Exalted be He) also says:
He it is Who has sent His Messenger (Muhammad صلى الله عليه وسلم) with guidance and the religion of truth (Islâm), that He may make it (Islâm) superior to all religions. And All-Sufficient is Allâh as a Witness.
(Part No. 3; Page No. 335) From this it can be seen that Jihad was legislated to take people out of the darkness into the light and let them accept Islam in crowds. It was also to remove Fitnah and protect Islam.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.