It is believed that the Four Evangelists, known as Matthew, Mark, Luke and John, were the authors of the gospels. However, this is a historical event that is still under debate by Catholic leaders.
If the gospels were written before 70 A.D., it is believed that they could have been written by the disciples of Jesus. If this is the case, it is argued that they are more legitimate because they were written based on first-hand accounts and interactions.
One of the main arguments that support this is the fact that they do not speak of the Jewish temple that was destroyed in 70 A.D. This was something that Jesus prophesied as being destroyed.