That is why the Israelites cannot stand against their enemies. (Joshua 7:12).
It matters not how strong you are. It matters not whether you have the greatest resources and talent. It matters not if you have the best plans and procedures. It will all fail if you have a break in your armor.
This is the message God was telling Joshua when he attempted to go against a small army at Ai that was their second battle in the Promised Land. Sometimes we try to figure out why we are not successful in an endeavor. We look at all aspects of our performance to see what went wrong. For the people of Israel it was not easily seen on the surface. Everything seemed just as it should be from Joshua's vantage, so when his army was soundly defeated, he cried out to God, "Ah, sovereign Lord, why did you ever bring this people across the Jordan to deliver us into the hands of the Amorites to destroy us?"
The people had been defeated because God could not bless them. One person had violated the covenant with God. They were not to take any possessions from the first battle. One person failed to live up to it. The whole army suffered.
Sin makes our armor vulnerable to attack from Satan. Satan then gains permission from God to attack us in the area where we have failed to uphold righteousness. If we break down in moral purity, Satan comes in and establishes a stronghold. If we give place to bitterness and unforgiveness, we will break fellowship with God and others. If we become money focused, we will fall into greed and deception. It is a viscous cycle.
Examine your armor today. Make sure you are not susceptible to attack. Begin from a solid spiritual foundation and your chances of success will be great.