>>728656
Okay so the first thing you should know is that the person you met is not a perfect Muslim. His beliefs are not fully inline with the Koran. Here's what the Koran says about the apostles:
>Said the disciples: "We are God's helpers [anṣāru llāhi]: We believe in God, and do thou bear witness that we are Muslims [wa-ishhad bi-'anna muslimuna]. Our LORD! we believe in what Thou hast revealed, and we follow the Messenger (Jesus); then write us down among those who bear witness."
This crap about Judas is later fanfiction that has nothing to do with Islam. In fact, Islam teaches that Saint Peter the Apostle was the first Imam. Recently, a lot of Muslims have taken gnostic anti-Christian stuff and re-appropriated it to be about Islam, even though gnostic anti-Christian stuff is 100% fake and about 90% of it contradicts Islam.
Now for the other stuff: Jesus was crucified and that's one of the most attested to events in history. In fact, his crucifixion story is not relegated to the four gospels, it's also in all epistles, the ancient writings of Jewish and Roman historians, New Testament apocryphal texts, and even the bulk of those gnostic gospels that Muslims love to say prove the Bible is corrupted. As for the gospel of Barnabas, that appeared in the 1500s, and it was clearly made by someone with neither knowledge of Greek or Hebrew (Jesus is referred to in the gospel of Barnabas as "Jesus Christ," but he denies being the Messiah, saying Muhammad will be the Messiah. Christ is Greek for Messiah.) The Gospel of Judas was written in the third century; it's a polytheistic text that says that Jesus was crucified, so it directly contradicts Islamic theology.
As for why those books aren't in the Bible, the reason is because they were written later by heretical groups and don't conform to the rest of the Bible. The four gospels were circulating together by 180 at the latest, and were written much earlier (the final gospel, the Gospel of John was finished at 110 at the latest). The gnostic gospels generally date far after this time. People were trying to add on to a finished collection.