Here, the LORD plainly declares that the children of Israel were doing something that never entered into His heart for them to engage in. Does that mean they surprised Him when they did it? No in no wise! He knew that they would do it, but He did not cause them to do it in the slightest. One might ask, "Why didn't He stop them?"  To which I would reply, "Why does He stop anything?"  God would be just to let us follow after our folly and destroy ourselves. He would be righteous to never ever show us mercy. He is still the sovereign Ruler whether He acts or not.  

Many people think that a lack of action implies a lack of ability. Such is not the case with God. He has more power than He has ever shown. The greatest power that He will show (which is still not the fullness of it for His power is infinite) will be the day that He raises up all of mankind in the resurrection and burns up the elements with a fervent heat. That will be the greatest display of power ever to behold, but He still has more than that! God does allow man to engage in His own folly from time to time for which He is duly punished and judged (the righteous daily at the judgment seat of Christ and the wicked at the final day to everlasting destruction). The LORD always repays in vengeance what is rightfully His. However, we should never fault God for either doing or not doing something. His ways are too wonderful for us, and our mode should be one of praise, honour, and glory. After all, He not only created us naturally but spiritually as well. What right have we to blame or complain or say to the potter, "Why hast thou made me thus?"