The Syriac language word "Injeel" is what the Quran uses for the term "Gospel", in the Koine Greek "euaggelion". It means "glad tidings" or "good news". In the "good news" of Jesus Christ, for example
Mar 1:1 The beginning of the gospel of Jesus Christ, the Son of God;
The subject of that Gospel is that Jesus Christ chose to sacrifice Himself on the cross to provide propitiation for the sins of all mankind who have faith in His shed blood.
Mat 26:28 For this is my blood of the new testament, which is shed for many for the remission of sins.
As to why God chose to have atonement of sin through shed blood perhaps some day regenerate persons can ask Him. The simple historical fact is that atonement of sin has come through blood since the beginning of the old covenant that God had with His chosen people the Jews. Whether when God allowed Abraham to sacrifice a ram in place of Isaac, when God was testing Abraham's faith, or the focus of the temple that God had the Jews build being an alter, on which to sacrifice animals to atone for sin.
Even many Muslims believe that the first drop of blood shed by a Muslim so-called martyr may provide propitiation for the sins of 70 of his nearest and dearest friends and relatives. They sometimes even throw a party for the martyr in celebration.
Well you could look at Christianity as being that same kind of celebration of when God became "manifest", or revealed Himself to us, in the flesh Jesus Christ, to save all mankind who believe in His shed blood, from sin. The perfect sin-free man to provide the perfect example to us all, and thus the perfect sacrifice though which we might be saved. The Lamb without spot
1Pe 1:19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
Rom 3:25 Whom God hath set forth [to be] a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
1Ti 3:16 And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory.
And the Quran on the subject
Surah 4.157 That they said (in boast), "We killed Christ Jesus the son of Mary, the Messenger of Allah";- but they killed him not, nor crucified him,......
So Mohammed taught the exact opposite of the whole subject of the New Testament/covenant and the good news of Jesus Christ. Indeed throughout the entire 2000 years of Christianity there has never been a single Christian that has denied that Jesus died on the cross to save us from sin through His shed blood, was entombed, resurrected and ascended into heaven. The simple fact is that if a person didn't believe that, they wouldn't be a Christian. It would be an oxymoron.
And as far as I know, there is not a single Jewish sect that does not believe that Jesus died on the cross. They reject that He is their Messiah, and that He was resurrected, but don't deny He died on the cross.
Religions teach or persuade their adherents as to what to believe. The evidence of the truth of the Word of God for example is revealed over 1600 years through many dozens of witnesses.
Even Satanists are taught to believe in Satan.
Yet unlike any other religion, Mohammed instructs Muslims what not to believe as an important part of their core doctrine. This makes Islam specifically an anti-another-religion, religion, by design. While being convinced of what not to believe, Mohammed left a void regarding what to believe.
Muslims are left in the dark as to who did die on the cross.
Indeed Islam is to Christianity as a negative is to a photograph.
The kinds of things that Christians are taught not to believe are false prophets, like Mohammed, for example.
...... but so it was made to appear to them, and those who differ therein are full of doubts, with no (certain) knowledge, but only conjecture to follow, ....
All Christians and Jews are thoroughly resolved as to Jesus death on the cross, yet when we ask Muslims who died on the cross we find Islam teaches a dizzying and wildly confused array of different theories, as will soon be detailed in this forum. Please go out and ask some for yourself and add to the list of stories.
In other words the irony is that Muslims are, in fact, exactly the way that Mohammed described Christians and Jews, "....full of doubts, with no (certain) knowledge, but only conjecture to follow...".
.....for of a surety they killed him not:-
