Judges 3:1-2 NIV ‘These are the nations the Lord left to test all those Israelites who had not experienced any of the wars in Canaan (he did this only to teach warfare to the descendants of the Israelites who had not had previous battle experience).
Most of the older generation of Israelites had seen God come through and defeat their enemy time and time again.
But this time God deliberately left some nations in the land so that the new descendents of the Israelites could practice their battles and gain experience in spiritual warfare. God knew that they needed exposure to these enemies to prepare them for what was ahead.
God also wants to train us for battle by giving us a rehearsal. By overcoming these spiritual principalities and powers, we are practicing for bigger ones to come.
This preparation is healthy for us and ensures we will trust God in bigger challenges.
Make sure you qualify for stronger invasion, by conquering the ones you face now.