Israel had a choice to make and they made the wrong choice. We are not altogether different from them although we live in a season of grace before God. One of the strategies that Satan used against them was to get them to harden their hearts against God. 

Jeremiah 32:33 KJV..And they have turned unto me the back, and not the face: though I taught them, rising up early and teaching them, yet they have not hearkened to receive instruction.

Hebrews 3:7-8 KJV...

 Wherefore (as the Holy Ghost saith, To day if ye will hear his voice,

8 Harden not your hearts, as in the provocation, in the day of temptation in the wilderness: