James 4:4 says essentially that friendship with the world is enmity with God (hostility or opposition). So being the world’s friend is to act in opposition to God or hostility to God.  But that’s exactly what we do with our sin.  We make friends with it.  We engage in sexual immorality and rather than repent and condemn it, we justify it.  We call it by other names.  We become comfortable with it.  We make it a friend.  And like other friends, we will defend it if someone points it all.  ”Your sexual impurity is sin,” someone says.  And we’re quick to come to its aid.  ”You don’t really know me.  We’re in love.  It’s not sin if we’re married in our minds.  Don’t you talk about my friend!”  The Bible tells us not to get cozy with our sin b/c our sin is a “friend” who’s trying to kill you!  That’s not a real friend.  Instead we’re told to put our sin to death.  There’s nothing more final than putting something to death.  Romans 8:12-14 is the classic text on “mortifying” to use an old word, the sins of the flesh.  We’re told to use the power of the Holy Spirit, which brings life, to kill the sins of the flesh, which bring death.  So we’re called to be sin killers not friends of sin.  Our church is looking from a biblical perspective at not wasting our lives this year.  There are few things that lead to a wasted life like unrepentant sin.  It lives and grows and takes over and before we know it we’re slaves to it.  The Christian must daily kill sin.  Taking the axe to the root of our “lusts” as John Owen puts it.  The axe that can take out the root of lust is Jesus.  Everything else is just lopping off the top, leaving the roots.  So we’re sure to have it sprout back up in little or no time.  I want to be a sin killer.  I’m too frequently not.  God help me put to death the desires of the flesh.