The most destructive force to mankind is his own heart. All of our sin starts from the heart. Our heart creates desires and desires sparks sins; the desire of power, the desire of flesh, the desire of recognition, the desire of wealth. This is the method Satan used to tempt Jesus. The tells us about guarding our heart. It is not guns, nature and illness that destroys mankind. Guns and killings are just a product of our sinful heart while if we have a loving heart, it will glow in times of calamities, disasters and illness. "The heart is deceitful above all things, and desperately wicked: who can know it?" – Jeremiah 17:9