Spiritual warfare doesn't seem to be talked about much these days outside Pentecostal circles. It's a dangerous shame.
There's a line in the Anglican baptism liturgy that goes something like this:
Fight valiantly a a disciple of Christ against sin, the world and the devil, and remain Christ's faithful soldier and servant to the end of your life.
One church I used to be at had changed it to:
Stand firm as a disciple of Christ against sin, the world and the devil, and remain faithful and obedient to Christ, to the end of your life.
It's linked to the fact that the Lectionary which most churches use tends to ignore the more military bits of the Bible, especially in Psalms. But I don't follow the RCL, so I've been reading them quite a bit recently. The other day, for example, I read Psalm 59.
Deliver me from my enemies, O God;
be my fortress against those who are attacking me.
Deliver me from evildoers
and save me from those who are after my blood.
See how they lie in wait for me!
Fierce men conspire against me
for no offence or sin of mine, Lord.
I have done no wrong, yet they are ready to attack me.
Arise to help me; look on my plight!
You, Lord God Almighty,
you who are the God of Israel,
rouse yourself to punish all the nations;
show no mercy to wicked traitors.
They can be quite difficult to read these days, because we don't have physical enemies seeking to kill us, like David did, and if we do then on balance we'd prefer it if God changed their hearts so they became our friends.
When we try to apply those Psalms to our lives, there are several helpful routes to take. We can see them as the first stage in letting go of anger – asking God to take vengeance rather than doing it myself. We can see them as Psalms sung by Jesus, entrusting himself to God and asking God to rescue him from attack, which God does in the resurrection. But lately I've found it helpful to read them through the lens of Ephesians 6:12.
For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.
As Christians, we are in a real battle. And it's no less real just because our opponents aren't physical people but ideas, temptations and spiritual forces, and we need to learn to fight them better. I'm finding it really helpful at the moment reading the "fighting Psalms" and thinking of the temptations I experience; the things that want to knock me off course in following God, and asking for his protection and rescue from them.
So when we get a decent hymn that is about spiritual warfare, I'm going to try to encourage folks to sing it...