The Lord reminds Israel that their mission is to take the land, even defeating the giants and Anakim. God would go before them and destroy them for the children of Israel. They were to destroy them quickly and drive them out.
The caveat here is that God also reminds them that they should not get arrogant or comfortable in their prosperity. The fact that God will drive out the giants was not because of their righteousness, but rather because of the nations’ wickedness. As a matter of fact, God still considered Israel a stiff-necked people. The only reason they were chosen was because of the covenant between the patriarchs and the Lord.
The Israelites’ rebellions were numerous: Horeb, Sinai, Taberah, Massah, Kibroth Hattaavah, and Kadesh Barnea. They complained against God, built a false God (golden calf), attacked Moses’s leadership, complained again, etc. One common denominator was the fact that Moses always interceded for Israel, and God relented from His punishment for their rebellion.
The moral of the story is this: no matter how your emotions get the best of you, no matter how much the glimmer of the world entices you, no matter how hard the battle may get, do not forget God and how He brought you into the blessings you now enjoy. He loves you and He wants to bless you, but He is not blessing you because of your merits, but because of His grace and mercy. Never presume upon His grace to the point that you take God for granted. Thankfulness and gratitude are the order of the day for the believer. Live in them!