2 Corinthians 10:4-5
For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ.

The power of a simple gospel tract, placed in the hands of a willing servant of God, can never be underestimated. It can lead a soul to Christ and transform a life of eternity.
Dwight L. Moody