God is following a pattern He established long ago in performing His creative efforts. He reveals it in His dealings with Israel, and He is still following it to this day.
Nothing in Deuteronomy 7:6-8 would give the average Israelite a puffed-up mind on the subject of God's calling of them to work in and through them for His creative purposes. He makes it plain that He did not deliver them or work with them because of anything they had already accomplished as a nation. They had been a bunch of slaves!
Through the apostle Paul, God exposes a humbling yet accurate truth about those He has called into His church. We must come to grips with it because a humble recognition and acceptance of this reality is necessary for His purposes. We can compare what God says about us with what He said about Israel in Deuteronomy 7. I Corinthians 1:26-31 describes us in this way:
For you see your calling, brethren, that not many wise according to the flesh, not many mighty, not many noble, are called. But God has chosen the foolish things of the world to put to shame the wise, and God has chosen the weak things of the world to put to shame the things which are mighty; and the base things of the world and the things which are despised God has chosen, and the things which are not, to bring to nothing the things that are, that no flesh should glory in His presence. But of Him you are in Christ Jesus, who became for us wisdom from God—and righteousness and sanctification and redemption—that, as it is written, “He who glories, let him glory in the Lord.”
God is following the same pattern in calling Christians into the church. We are described as “foolish,” “weak,” “base,” and “despised.” It sounds a great deal like lowly Israel. The only major difference is that He called Israel as an entire nation at once, but He calls Christians into His church one at a time. Incidentally, when He calls us, we, too, are a slave people—unwitting slaves in most cases, living under Satan's thumb and taking orders from him.