The world is the sphere of the devil’s rule (2 Corinthians 4:4).  There is nothing Satan wants more than for us to conform to this world.  He knows that the more worldly-minded we are, the further away from God we drift.  John put it like this: 

1 John 2:15-16 (ESV)
15  Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. 16  For all that is in the world—the desires of the flesh and the desires of the eyes and pride of life—is not from the Father but is from the world.

We are all serving either God or Satan.  Jesus said that we cannot serve both of them because if we love one, we hate the other (Matthew 6:24).  So, since the love of the Father is not in us if we love this world, to love it is to be devoted to the devil.  Do not play into the devil’s hands by being worldly-minded.  Instead, follow the exhortation of Paul.

Romans 12:2 (ESV)
2  Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.

Do what the devil does not want you to do—separate yourselves from this world.  Listen to Paul in another place:

2 Corinthians 6:17 (ESV)
17  Therefore go out from their midst, and be separate from them, says the Lord, and touch no unclean thing; then I will welcome you,

Paul is quoting Isaiah 52:11 here.  The truth is, God has always wanted His people to be separated from the world and the sinfulness of it.  This begins with the heart.  Paul said we must be transformed by the renewal of our minds.  Our focus should be on spiritual things as we strive to live by God’s will.  It is only when we have the mind of the Spirit that we end up pleasing God (Romans 8:5).  If, instead, we are worldly-minded, or, as Paul puts it, we mind the things of the flesh, we will never please God.

Romans 8:7-8 (ESV)
7  For the mind that is set on the flesh is hostile to God, for it does not submit to God’s law; indeed, it cannot. 8  Those who are in the flesh cannot please God.

Do not make this world the focus of your life.  If you do, you will inevitably engage in the things of this world and fail to be holy.  Choose God’s way and do what the devil does not want you to do.  Choose to set your mind on things above, where Christ is (Colossians 3:1-2), and you will separate yourselves from the world.  If you do this, you will be demonstrating who you love and choose to serve.  You will be proving that God is your Master.

When you do things that the devil does not want you to do, you will make him mad, but you will be pleasing God.  Which would you rather do?  Pleasing the devil might bring some temporary satisfaction, but in the end, you will find yourselves with him in torment (Matthew 25:41).  Pleasing God will take some sacrifice now but will lead to eternal life in glory (Matthew 25:34).  Let us all choose to do the things that the devil does not want us to do.  We will never regret it.

As you wind down for the night, think about these things.