Perhaps they did not like being out of control. They chafed under the notion that they had to do anything to get that favor from God. They wanted autonomy. Interesting that if you look at the roots of that word, autonomy, it means self ruling. They did not want to submit to God – even if it meant that they did not get the promised blessing.
Are we much better? We are not saved by keeping the law or by works – that is the crystal clear message of the Gospel. But that word “diligence” shows up in relation to how we approach our relationship with Christ. 2 Peter 1:5ff, 10, 3:14 is one thread that comes to mind. Peter describes the Christian life as one of diligent application of faith. Is that your experience? It is the case that believers you know are diligently following Christ? What would that look like?
For the most part we seem to be diligent in our careers, our recreation, and in the support of our favorite team. I wonder if like Israel we are missing out on the astounding stuff that God has promised.