I'm very curious as to exactly what "offensive spiritual warfare" would actually entail. Would it be praying for those you believe are possessed or inclined to 'satan'? Is it performing some sort of long-distance exorcism? What?
Sometimes people pray in order to bind the spirit which blinds those they want to preach to.
But binding that spirit is not what men are held bound by, for it is their self life which binds them, which is called the "flesh" in the Bible.
and it is only some of those who call on God to deliver them from that bondage who will accept the word concerning Jesus and His requirements of entering into His Kingdom.
for those who love their flesh more than Jesus, will turn back as shows the parable of the sower.
And the followup question would be how do you determine who or where or what these evil "demons and principalities" are, that you wish then to attack?
The principalities and powers of satan are among men, and it is folly to try to free men from them if they do not want to be set free, but in speaking the truth publically the seed will always fall on all kinds of ground.
Which is why privately speaking to individuals one is sent to is less of a problem but some men are sent to speak to many at one time which is good that large meetings are arranged for this rather than in the park.
If God does some great miracle then all the satanists will turn up and that is not good or necessary for the preaching of the gospel to those who God does draw to come.
For men are so prone to follow the miracles or some great preacher rather than give their life to Christ AFTER they believe as did Abraham, the father of the faithful.
LA