In the Old Testament, time after time the Israelites had to trust God for victory over an enemy because their back was to the wall and there was no other way. Often it was God himself who arranged things that way. He did it so there would be no doubt in the minds of his people that he was the one who saved and delivered them.
Over time though, the hearts of his people grew dull. By the time Jesus came upon the earth the Jewish leadership thought they could manage their own enemies. It was so bad they actually thought Jesus was the enemy.
Listen to the Pharisees as they tried to decide how to handle their “Jesus problem.” “If we let Him alone like this, everyone will believe in Him, and the Romans will come and take away both our place and nation.” (John 11:48) Not only did they not recognize their Messiah but they abdicated both power and trust to the Roman Empire. Not such a good idea was it? In the end, Rome destroyed their nation anyhow.
We need to guard ourselves from dull hearts too. How easy it is to look at something other than God and invest it with power and trust. How easy to think that we will manage our own life and assure our own outcome.
Better to follow this advice in Proverbs: “There is no wisdom, no insight, no plan that can succeed against the Lord. The horse is made ready for the day of battle, but victory rests with the Lord.” (Proverbs 28:26)
Cultivating trust is the best insurance against a dull heart.