[Hope]

The disciples of Jesus, as mentioned in the Quran as "the white-garbed ones", were Muslims.

The Quran didn't mention their names so we don't know.

You don know their names but you know they are moslems 

To be considered disciple of Jesus, they must have understand and learn the teachings of Jesus .do you agree? So it is possible for the Injil to be written down in a book form after Jesus

Those disciples were Muslims.
Muslim means submitting to Allah without associating partners to him


“When Jesus sensed disbelief from his people, he asked, “Who will stand up with me for Allah?” The disciples replied, “We will stand up for Allah. We believe in Allah, so bear witness that we have submitted.”Quran 3:52