"Jesus then left that place and went into the region of Judea and across the Jordan. Again crowds of people came to him, and as was his custom, he taught them. 2 Some Pharisees came and tested him by asking, ‘Is it lawful for a man to divorce his wife?’ 3 ‘What did Moses command you?’ he replied. 4 They said, ‘Moses permitted a man to write a certificate of divorce and send her away.’ 5 ‘It was because your hearts were hard that Moses wrote you this law,’ Jesus replied. 6 ‘But at the beginning of creation God “made them male and female”.[a] 7 “For this reason a man will leave his father and mother and be united to his wife,[b] 8 and the two will become one flesh.”[c] So they are no longer two, but one flesh. 9 Therefore what God has joined together, let no one separate.’ 10 When they were in the house again, the disciples asked Jesus about this. 11 He answered, ‘Anyone who divorces his wife and marries another woman commits adultery against her. 12 And if she divorces her husband and marries another man, she commits adultery.’"The reason for quoting the Markan passage rather than the Matthean parallel is because I believe the significant change in the Matthew passage - ie the exception for adultery - to be an addition to what Jesus himself taught. That is, I believe that a major thrust of Jesus' teaching on marriage to be a prohibition on divorce in all circumstances. To put that differently, I do not believe that Jesus allowed adultery to be a reason for divorce; I think that this is a Matthean addition brought in because Jesus' teaching was too hard for the community to accept - in other words, that the 'hardness of heart' Jesus refers to was still present in the early Christian community.
More significant, however, is the context for that teaching about divorce, which is the 'one flesh' reference back to Genesis. I want to spend a lot of time thinking through this passage - much more than I plan to incorporate in a single post - but for now I simply want to register that this passage, in the Markan form, is the second foundational text for my explorations.