Why did God stop calling Israel 'My people' and start calling them 'Thy people'?
Israel's stiff-neckedness and rebellion led God to stop calling them 'My people' and instead tell Moses, 'Thy people,' meaning 'Your people.' In Matthew 23, after Jerusalem would not be gathered, Jesus similarly says their house is left desolate, marking that same separation.
Les explains that the pattern began when God dealt with Israel under Moses. At first God called them 'My people,' but after their stiff-neckedness and rebellion He finally told Moses, 'Thy people,' or 'Your people.' He did not call them 'My people' anymore. Les then connects this to Matthew 23:37-38, where Jesus says, 'O Jerusalem, how I would have gathered you like a hen gathers her chicks, but you would not,' and then declares, 'Behold, your house is left unto you desolate.' The pronoun 'your' should be underlined because it shows the same shift, and Les notes God does the same thing with the temple.