Three main obstacles to growth in the Christian life is society, devil and flesh. 
        
             
        
        
        
Answer:
I would consider the adoption of gun powder 
Explanation:
gun powder changed the world and is still widely used today for guns, explosives and rockets.
 
        
             
        
        
        
ONE OF THE most bizarre (and fascinating) stories of the Revolutionary War is that of Deborah Sampson, a New England infantry “man” who fought bravely in George Washington's Continental Army. ... The War for American Independence been raging for six years, and Sampson intended to join the fight.