There is an extreme view of the origin of the gospels contaminated by the German higher critics of the nineteenth century, that holds that the Gospels were late documents cobbled together by people in the second century who did not know Jesus.
Modern scholarship suggests that all 4 evangelists were contemporaries of Jesus and the three synoptic gospels were written within 20 years of the death of Jesus. The incident of the young man who lost his clothes puts John Mark at the arrest of Jesus, Matthew was himself a disciple, Luke was a confidant of both Mary the mother of Jesus and Peter and he was later a companion of Paul whose own writings predate the gospels, even though he never met Jesus in His earthy lifetime. John's gospel is later but he was a very old man when he wrote it and there is no reason to believe it was written by anyone other than John the beloved disciple.
As for Jesus' own sayings, he claims to have come not to negate the Law but to fulfill it. The Old Testament apparent anomalies were pictures of the Christ to come. This same Jesus speaks more about the Hell to come than any other person in either testament and will come to judge the world. He is not the milksop that liberal Christians claim him to be and though for now he offers salvation, that offer is not for all time. After we die there will be no second chance and then if not covered by his death and resurrection, our sins will surely find us out. It is then that he will confront us with, "I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink, I needed clothes and you did not clothe me, I was sick and in prison and you did not look after me. ... I tell you the truth, whatever you did not do for one of the least of these you did not do it for me ... then they will go away to eternal punishment."