Background:
In Matthew 13, Jesus teaches publicly and then explains privately to his disciples
In Matthew 15.1-20, Jesus is teaching publicly about defilement and about the Pharisees being more concerned with traditions than with God’s Word . We should expect a private explanation.
In John 4, Jesus talks with a woman at a well, and never seems to be talking right to her. He seems to talk around her.
John 10 has lots of sheep language, including: "I have other sheep that do not belong to this fold. I must bring them also, and they will listen to my voice. So there will be one flock, one shepherd." (John 10.16)
The RCL appoints Isaiah 56 to be heard alongside this reading. Isaiah 56 includes:
Thus says the Lord God,
who gathers the outcasts of Israel,
I will gather others to them
besides those already gathered.
Another take on the pericope - Jesus Explaining His Mission to His Disciples:
Hopefully, the disciples and the readers of the Gospel are thinking at this point. Oh, so faith is a matter of the heart (15.19). We’re supposed to look at people’s faith and not at earthly markers of belonging. And we’re all just lost sheep. Jesus, you could have just said that…
Notes:
I have no need to defend God’s unchangingness. God changes the divine mind in Scripture. If the Calvinists have a problem with that, let them deal with it.
I don’t mind using more than one Gospel for interpretation.
I reject the idea that this lesson revolves around Jesus’ humanity, as if racism and bigotry was inherent to human nature before the fall. Jesus, the new Adam, is not tainted by that.
I reject the idea that Jesus has given up some of the divine nature in order to “learn” in this reading. Such teaching falls into heresy by not claiming that Jesus is fully divine.
Art: Watanabe, Sadao, 1913-1996. Woman of Canaan, from Art in the Christian Tradition, a project of the Vanderbilt Divinity Library, Nashville, TN. http://diglib.library.vanderbilt.edu/act-imagelink.pl?RC=57538 [retrieved August 16, 2020]. Original source: https://americanart.si.edu/artwork/woman-canaan-26809.