I have heard a lot of people ask questions about God and why He appears to be so different in the Old Testament than He does in the new. Particularly, God can seem lacking in grace – such as when He tells Moses and the Israelites that they will blot out different peoples from the earth. How can a good God do such a thing? In order to understand the answer to this question, we need to consider what God is trying to accomplish – namely, bringing salvation to all peoples on the earth. From the beginning, God created man for a relationship with Him, but man sought his own direction in life. Why didn't God force man into the relationship? To do so would take away free will. If we no longer have a choice, then we are no longer free beings.
At this point in the story, God has redeemed Israel from the hands of the Egyptians, and He is leading them to the Promised Land. However, God does not want their hearts to be torn away from Him as had been the past reality. Therefore, God's plan was to get rid of any hindrances that would keep the Israelites from following Him wholeheartedly. The plan for Christ's redemption was already in existence, so God knew that salvation would come to the gentiles, too, through this nation. He desired their whole-hearted devotion then just as much as He desires our whole-hearted devotion now. What is in the way of your complete devotion to God? Perhaps He wants to rid you of that very thing so you might be wholly committed to Him.