The Principle of Physical Absorption From Abraham Onwards

There is a sense in which there was Israel, but then there was the true Israel, of God, even under the old covenant. And so once the Messiah comes, that principle of physical descent just it drops away and becomes about faith only. It's a strong theological, exegetical argument in response to a man whose works we've come to love and appreciate John Murray. But who makes us a bold statement that simply cannot hold up against a whole theology of children in the New Testament?