The Gospel of John was written in Greek Koine and was therefore intended for an audience that spoke this language, which was spoken in Egypt and most of the Near East, except the Palestinian Jews. Scholars say that the gospel was originally written for a Gnostic community, now known as the Johannine community because the Gospel is traditionally associated with John.
John was subsequently amended to remove some of the more overt Gnostic content, to make it more acceptable to a broader Christian audience.
John wrote to evangelize the Jewish people.
It is almost universally believed that the Gospel of John was written for a community now known as the Johannine community. Scholars say that this community seems to have been a Gnostic Christian community, but the Gospel shows signs of having been subsequently amended to make it more acceptable to the centrist Christian tradition.
If you look closely you will see that Brother John is writing to convert a sinner.
It was probably written as a circular letter from Ephesus about 85-95 AD to the believers of the Roman province of Asia, including the churches mentioned in Revelation chapters 2-3. John wrote out of concern for the spiritual children for whom he was responsible.