In any Bible study across the country, this statement ("The Israelites were dumb") almost inevitably then leads to another statement, "Wow, it makes me realize just how like the Israelites I am." Meaning, we too are fallible and stray too often from God. This is true; we as Christians make all kinds of bad decisions and our faith seems much smaller than a mustard seed at times.
But this idea that we're just like the Israelites is kind of making me mad--on God's behalf. For it diminishes the work of the Holy Spirit.
The Israelites were under the old covenant--God set out rules and said, "Obey these." They were very bad at it. But we are under the new covenant that Jeremiah prophesies:
"The time is coming, when I will make a new covenant with the house of Israel and with the house of Judah...This is the covenant I will make with the house of Israel after that time, I will put my law in their minds and write it on their hearts...No longer will a man teach his neighbor, or a man his brother, saying, 'Know the Lord,' because they will all know me...For I will forgive their wickedness and will remember their sins no more."
Hebrews 8 and 9 reveal that this is the very covenant that we as followers of Christ are part of.
Why does it matter? Because we are fundamentally different from the Israelites. We are not just fallible humans trying hard and failing to "be good." As Christians who have the Holy Spirit of God, he has put his law in our minds. He has written it on our hearts. We can know him in a way that the Israelites never could because our sins have been forgiven.
If we only think of the Israelites metaphorically, it's easy to say, "oh yeah, we're just like them." But we're not. Do you know any Christians burning babies? Do you know any offering their young daughters as sex mates to appease gods? We can say we're idolatrous (which we are at times), but don't diminish the work God has done!
God has redeemed us and written his law on our hearts in such a way that we are enabled to live radically different lives.