Here is an excerpt from an article I wrote earlier this year:
Decoding the Opponent's Playbook: Our Self
As Christians, we constantly battle our sinful natures. Through the atoning sacrifice of Christ we are already justified before God. Nevertheless, our sanctification will not be complete until we see Christ and are perfected. Until that day, we battle. Our selfish nature has one basic way in which it opposes us; sin. This is the one-word playbook of the opponent we find in our own heart. Thomas Watson, the 17th century puritan author and pastor, in his book entitled Heaven Taken by Storm suggests two ways in which we battle ourselves; first, we mortify sin, and second, we provoke ourselves to Christian duties. Watson suggest that to mortify, or put to death, sin we must both avoid temptations and fight sinful tendencies with faith and prayer. And to provoke ourselves to Christian duty we must participate in the disciplines that have nourished the saints from Christianity's onset; reading the Word, hearing the Word, prayer, meditation, holy conversation, fellowship, and the like.
Decoding the Opponent's Playbook: The World
The world is our second opponent. Its playbook, again according to Thomas Watson, consists of the deceitfulness of what we want and defilement of what we have. John Piper presents the same idea in his sermon entitled Do Not Love the World (By John Piper. © Desiring God. Website: desiringGod.org). “The world is driven by these two things: passion for pleasure and pride in possessions.” 1 John 2:16 reads, “For all that is in the world—the desires of the flesh and the desires of the eyes and pride in possessions—is not from the Father but is from the world.” The deceitfulness of what we want is described as the desire of the flesh and the desire of the eyes. The pride of life, according to Piper, is “what you possess—the things you have ... the pride of life—refers to the pride in what we do have.” For both Piper and Watson, this is a battle of desire. Watson writes, “The sin is not in using the world, but in loving it ... A true saint is crucified in his affections to the world ...” Piper echoes this idea, “ ... let us desire nothing but God. Possess nothing but God; pursue nothing but God.”
Decoding the Opponent's Playbook: Satan
The final opponent the Christian encounters is Satan. A final reference to Watson's work, Heaven Taken by Storm, will allow us to peer into the devil's playbook. “Satan opposeth us both by open violence, and secret treachery. By open violence, so he is called the Red Dragon; by secret treachery, so he is called the Old Serpent. We read in Scripture of his snares and darts; he hurts more by his snares than by his darts.” The darts that Satan employs, corresponding to 'open violence', are the blatant fears, passions, and lusts that regularly assault our souls. These are temptations that use a full frontal attack to undermine the work of God in the saints. The snares, representing the 'secret treachery', refer to the subtle tactics of temptation. These are numerous and devious; drawing men to evil under pretence of good, tempting with the good and beautiful, enticing to sin gradually, deceiving to sin with lawful things, or persuading men to do evil for good ends. Faith is Watson's weapon for the devil. It is in faith that we resist the devil and he flees. It is faith that keeps the castle of the heart from yielding. It is faith in our Saviour's death and resurrection that convinces us we fight against a defeated foe.