It is when believers are out of answers, confidence, and strength, with nowhere else to turn but to God that they are in a position to be most effective. No one in the kingdom of God is too weak to experience God’s power, but many are too confident in their own strength. Physical suffering, mental anguish, disappointment, unfulfillment, and failure squeeze the impurities out of believers’ lives, making them pure channels through which God’s power can flow.
John MacArthur