After forty years of wondering and grumbling the people just didn’t get it. After all the miracles in Egypt, the manna, and the quail from heaven, the people did not understand the grace of God. Moses gave the reason. "To this day the Lord has not given you a heart to know, nor eyes to see, nor ears to hear" (Deuteronomy 29:4).
Moses also gave this promise. "The Lord your God will circumcise your heart and the heart of your descendants, to love the Lord your God with all your heart and with all your soul, so that you may live" (Deuteronomy 30:6). This promise is in keeping with the Great Commandment. "You shall love the Lord your God with all your heart and with all your soul and with all your might" (Deuteronomy 6:5).
The New Testament picture is the same. Jesus says, "If you love Me, you will keep My commandments" (John 14:15). The apostle John declares, "This is the love of God, that we keep His commandments" (1 John 5:3). The apostle Paul says of fellow Christians, "The love of God has been poured out within our hearts through the Holy Spirit who was given to us" (Romans 5:5). Hearts inclined toward the love of God require spiritual awakening and rebirth. This is why Jesus declares, "You must be born again" (John 3:7).