Why did God stop calling Israel 'My people' and call them 'your people'?
Because of Israel's stiff-neckedness and rebellion under Moses, God stopped calling them 'My people.' He told Moses they were 'thy people' or 'your people,' no longer claiming them as His own. Their disobedience caused Him to disown them. The same pattern appears with the temple.
Les explains that just as God dealt with Israel under Moses, He started out calling them 'My people.' But after their stiff-neckedness and rebellion, He finally told Moses, 'Thy people. Your people.' So He didn't call them 'My people'; He said 'Your people.' Les points out that Jesus does the same thing with the temple in Matthew 23:38, saying, 'Behold, your house is left unto you desolate,' and He underlines the pronoun 'your.' This shift shows that because of their rebellion and rejection, God no longer claimed them as His own.