The Readings: Exodus 15:22-16:10; 1 Peter 2:1-10; John 15:1-11

Peter continues to expound his new exodus theme. Arriving at Sinai Israel heard: “Now therefore, if you obey my voice and keep my covenant, you shall be my treasured possession out of all the peoples. Indeed, the whole earth is mine, but you shall be for me a priestly kingdom and a holy nation” (Exod 19:5-6a). Peter: “But you are a chosen race, a royal priesthood, a holy nation, God’s own people, in order that you may proclaim the mighty acts of him who called you out of darkness into his marvelous light” (2:9). So William Temple, Archbishop of Canterbury during WW II: “The church exists primarily for the sake of those who are still outside it” (for variants, see here).
That’s the goal; in today’s Exodus reading Israel is, like us, very much a work in progress. Temple again: “Thou canst do all things. I have nothing. I am not fit to offer the meanest service. Surely God will first require and help me form a character worthy to serve him, and then appoint me my task. No; in point of fact it is only through service that such a character could be formed.” (Readings in St John’s Gospel, cited in Schmidt’s Glorious Companions). So perhaps we can be patient with ourselves and those around us.
In that last quote Temple could have been talking about today’s reading from John. It’s one of Jesus’ two retellings of Isaiah’s Song of the Vineyard (5:1-7), the other being the parable of the wicked tenants (Matt 21:33-46 and parallels). Isaiah’s song concludes: “For the vineyard of the LORD of hosts is the house of Israel, and the people of Judah are his pleasant planting; he expected justice, but saw bloodshed; righteousness, but heard a cry!” I’m puzzled. When we explore what sort of fruit God is seeking in John 15, why doesn’t the exploration start with Isaiah 5?