few followers. He did not preach to the Romans or Greeks or other pagans, he preached mainly to Jews, and in several cases to Samaritans, since they had a very similar religion and were also descended in part from the ancient Israelites. God, in his wisdom, did not want the preaching to be done to pagans yet. So when Romans, and Greeks, and Egyptians and other pagans heard about Jesus, they were not interested. So even if they met Jesus, they would not bother writing about him. And very few pagans met Jesus. So almost no pagans knew about him. Some Jews did know about him, but in the great majority of cases they did not believe him. They thought he blasphemed against God, and he worked on the Sabbath, so they thought he was evil. And he did not save the Jews from Roman rule, like the Jews thought the Messiah was going to do. So they thought he was just one of the many false Messiahs, which were so common in that time. So it is not surprising if none of them bothered to write about meeting him. Though maybe several of them did write about him, but since such writings were not copied again and again by copyists, the writings did not survive. And Jesus's disciples were not invited to write down any dictation by Jesus. Jesus was not dictating anything. The disciples were invited to simply listen and learn. It was not the time to write about Jesus yet. But then later God inspired Jesus' disciples Matthew and John to write an inspired biography of Jesus, and he similarly inspired two disciples of disciples, Mark and Luke, to do the same. So they wrote, and since their writings were inspired, and therefore holy, they were being copied again and again by later copyists, so that is how we have ancient copies of those gospels, even though the originals of course did not survive. And Peter, who was also one of the original disciples and so knew Jesus personally, wrote about Jesus in his epistles, and those epistles were also inspired. And Jesus's brothers James and Jude, who knew Jesus already from their childhood, they also wrote inspired epistles mentioning him a number of times.
So that is why we don't have any writings by contemporaries of Jesus who were critical of him, even though they had met him. Very little of what was written in those ancient times has survived. In fact we don't have any critical works about Muhammad written by his contemporaries that have survived, even though Muhammad ended up being better known in his lifetime, since his troops conquered and unified Arabia. So I have heard on the radio a Catholic author who wrote a book claiming Muhammad did not exist, he was a myth. This author also writes that when Arabs were conquering Christian lands in the beginning, the Christians were writing of the Arab conquest, but were not writing anything about Islam or Muhammad. So he thought that Islam and Muhammad were invented later, by the Arab conquerors, to replace their pagan religion. Of course the same author does believe Jesus Christ exists, that is why he is Catholic. But even atheists generally do believe Muhammad did exist. For one thing, a couple of ancient mosques were found with the direction of prayer towards Jerusalem, proving that Muhammad originally directed his followers to pray toward Jerusalem, and only later toward Mecca. Though, while I have not read his book, I suppose he might argue that when the Arab conquerors invented Islam, they at first directed Muslims to pray toward Jerusalem and then they changed it to pray toward Mecca. But this story, that only after the initial conquests of Egypt, Syria etc., then somebody invented Islam and convinced the Arabs to believe in it, wrote the Qur'an and wrote many of the Hadith, which are traditions of what Muhammad told his followers, which according to Islam were written by a number of contemporaries of Muhammad, and so all the stories about Muhammad and his wives and his relatives, were all invented, I just don't find it to have any credibility. Such an elaborate invention would not have convinced many Arabs to abandon paganism and believe in Islam.