I would like to provide feedback to the case of that test paper where students, upon facing the question “Allah is the [blank] worshiped by Jews & Christians,” are supposed to give the answer “same God.”
This is a factual error for the following reasons:
*** Allah has no son vs. Jesus, the son of God
Quran 5.17 commands: “Surely, in disbelief are they who say that Allah is the Messiah, son of Maryam (Mary) (…)”
Quran 5.72 commands: “Surely, they have disbelieved who say: ‘Allah is the Messiah Isa (Jesus), son of Maryam (Mary).’ But the Messiah Isa (Jesus) said: ‘O Children of Israel! Worship Allah, my Lord and your Lord.’ Verily, whosoever sets up partners (in worship) with Allah, then Allah has forbidden Paradise to him, and the Fire will be his abode. And for the Zalimun (polytheists and wrong-doers) there are no helpers.”
Islam regards Jesus as a prophet and messenger of Allah, however, it rejects that he was a divine figure or the son of God. Associating a partner in worship to Allah, thereby rejecting his oneness (tawhid) is called shirk, and it is a severe sin punished by death.
Since Islam denies the Holy Trinity, there cannot be a common basis in religion between Muslims and Christians.
Jesus certainly never told the Jews to worship Allah. This claim is in the Quran because the concept in Islam is that every prophet (Abraham, Jesus etc.) taught Islam, but the Jews and the Christians distorted it to create their false religions (i.e. Judaism and Christianity). That is why Muslims in their prayer call Christians “those who go astray” (Quran 1.5-7; Sahih al-Bukhari 12:749).
*** The crucifixion did not happen vs. the crucifixion happened
Quran 4.157 commands: “And because of their saying (in boast), ‘We killed Messiah Isa (Jesus), son of Maryam (Mary), the Messenger of Allah,’ – but they killed him not, nor crucified him, but the resemblance of Isa (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. Isa (Jesus), son of Maryam (Mary) A.S.].”
Muslims deny the crucifixion, thereby the sacrifice of Jesus for atonement and salvation.
*** In Islam, Jesus will destroy Christianity and Islamize the world
Sahih al-Bukhari 3.43.656: “Narrated Abu Huraira: Allah’s Apostle said, ‘The Hour will not be established until the son of Mary (i.e. Jesus) descends amongst you as a just ruler, he will break the cross, kill the pigs, and abolish the Jizya tax. Money will be in abundance so that nobody will accept it (as charitable gifts).’”
Jesus will break the cross, thereby will destroy Christianity.
The Jizya is a tax Christians and Jews must pay in order to not get killed by Muslims – it is a sort of mafia-style protection money in accordance with Quran 9.29. The Jizya will be not collected after the return of Jesus because there will be no Christians and Jews.
That is definitely not something Christians believe in.