Deuteronomy 7 records instructions to Israel to conquer the promise land without showing any mercy to its inhabitants. Israel was not to intermarry with them nor make any treaty. The core issue was Israel's status as God's chosen people in covenant relation with him. They were to remove all idolatry and all false religions from the land. In this way they would live as a distinct people among the nations. If they did so, they would experience all the blessings of the Covenant established through Moses.
Christians are under the new covenant inaugurated by Christ. Christians are not a nation with land and an army. What does Deuteronomy 7 have to do with us? As Israel physically did, we are to ruthlessly remove idols from our hearts. As Israel was, we are to be distinct as Christians by not being spiritually mismatched in marriage. As Israel was, we are a distinct people with a glorious hope for living in God's future kingdom. As Israel was, we are signposts pointing to Jesus and calling others to know him. How might the Lord be calling you to greater faithfulness and distinctiveness this week?