The power of belief, indeed.
There was any number of writings produced during the 1st and 2nd centuries, but I cannot see the Gospel of Barnabas listed among them.
The dominant sector of the 4th century Church decided which writings it agreed with (aided by the Roman Emperors) and their actions determined orthodoxy. They made mistakes with their selections, incorrectly ascribing several texts to Paul, and taking in 2nd century creative writings such as Luke-Acts.
Following Paul's death, the first Gospel written was by his friend Mark (not Jesus' disciple). This was followed by one of the opposite camp, Matthew. It is thought that Matthew's gospel was placed first since it provides the best bridge from the Hebrew texts to those of Jesus' followers. Paul's followers triumphed and his Christian religion became the orthodox model.
Doug