The Arabic word injil can easily lead to confusion, as it is used by Arabs in different ways.
The usage of injil by the Arab Christians comes from the Arabic translation of the New Testament, where it is used for “gospel.” The word injil is derived from the Greek word evangelium, which means “good news.” Four parts of the New Testament are called “gospel”; they are the gospel according to Matthew, the gospel according to Mark, and according to Luke and John. The literal translation from Greek would give the title “The good news according to Matthew,” i.e. the message of the good news as recorded by Matthew.
According to the Qur’an there is one book with the name Injil. As Moses received the Thora, so Jesus received the Injil (Sura 5:46, 19:30, 57:27). For a Muslim reading the New Testament, the natural conclusion is that Christians believe Jesus received four books. This easily leads to the thought that the Christians must have changed the New Testament. Therefore it is important for both Christians and Muslims to know what each mean when they speak about the Injil.
The confusion can be taken away when one realizes that for the Muslim the Injil refers to the whole New Testament and for the Christian to the good news. Some Arabic translations of the Bible use the Arabic word bushra for the Greek word evangelium, as bushra means “happy news.”
So, Christians have only one Injil, with four reliable records of witnesses of the good news that Jesus is the promised Messiah; the servant of God who suffered for the sins of all people, so that God may forgive them.