Son of God or not, Christ came to speak to us and share his message. It follows that this would have been most carefully recorded.
And even then there are problems. Matthew 19:9 and Mark 10:11 both quote Jesus discussing divorce. Both verses say marrying another person after divorce is adultery, though Matthew's quote includes an exception for fornication, sexual immorality or unfaithfulness, depending on the version. Which one is correct?