Children love the story of how young David was able to kill Goliath with one small stone flung from a sling. Goliath never envisaged he could be killed by a small shepherd lad. But as is so well recorded David went forward with words ‘ I come against you in the name of the Lord Almighty The power was the Lord’s, the stones the instrument of death.
David was no soldier or skilled fighter, but God had been preparing him for this day for years. His sling practise against the wild animals had been his school of learning.
Likewise God does not suddenly use us to defeat the devil. It takes years of preparation in reading the Bible, learning passages, praying and pursuing Christian fellowship. We will then be ready when the day comes to fight our Goliaths on His behalf.