In a battle, if you don't know who the enemy is, you can't win the war. The enemy is not us . We are not the enemy, but we can take action to stop the enemy. The first step is to identify the enemy in our own mind. This is called discernment .
Sin can be very subtle.
For example, one might think that helping an elderly lady across the street is a very kind deed. Sin is not just words. It has power. The more a sin works in our life, the more powerful it becomes. As a child we may see dad lose his temper.