The Kingdom is forcefully advancing: Matthew 11:12

Preamble
The interpretation of Matthew 11:12 is difficult.  NRSV: "From the days of John the Baptist until now the kingdom of heaven has suffered violence [or NSRV's alternative reading: has been coming violently], and the violent take it by force."  I will offer an argument for taking "has suffered violence" [biazo] as forcefully advancing, that is, as middle and not passive.

Spiritual Warfare
Jesus and the evil spiritual powers did not enjoy each other's company.  Demons seem afraid of Jesus asking him if he will destroy (Mk. 1:24) or torment (Mk. 5:7) them.  The fear seems to be based on Jesus' power to make the demons do something against their will.  The fear is well-founded because at Jesus' command demons are cast out sometimes it seems with great pain (Mk. 1:26).  How does Jesus' word have this power?  Clues could reside in the verbs used to describe Jesus' response.  In Mark 1, Jesus rebukes (epitiman) the demon and tells it to be silent (phimoo).  Scholars have argued that the term for "rebuke" corresponds to the Hebrew (ga'ar) which in the Old Testament is often paired with words such as "destroy", "vanquish", and "trample" (see especially Zech. 3:2).  Also, the term for "be silent" means in other contexts "to muzzle" or "to strangle".  We just don't know the physics of the metaphysical but somehow Jesus' power extends to the spiritual realm in such a way that "forceful" language is used in scripture.

"Force" language is also used to describe Jesus' overall stance versus the evil spiritual powers.  Jesus taught that the strong man must be bound before his property can be plundered (Mk. 3:27/Mt. 12:29/Lk. 11:21-22 [Luke adds the term "overcomes" or "attacks"]).  Again, Jesus' actions are described using "force" language.

Jesus interaction with the evil powers is part and parcel to the advancement of the Kingdom of God.  Jesus claimed that his exorcisms are by the finger of God (Lk. 11:20) or the Spirit of God (Mt. 12:28) and that they prove the Kingdom has arrived.

Matthew 11:12
Given the above it would make sense for Jesus to say that the Kingdom of God is advancing forcibly.  This make sense also in the immediate context.  Jesus had told John's disciples, who had come to question whether Jesus is the one to come, to report what they have seen and heard.  He then lists actions indicative of his ministry (see Mt. 11:5).  Exorcisms are not specifically mentioned in this list but exorcisms are mentioned in summaries of Jesus' ministry (Mt. 8:16).

Scholars have also argued that it could make sense to say "the Kingdom advances forcibly (biazo), and violent people (biastes) have been raiding it."  D. A. Carson has argued that a term can be used with two different senses, a phenomenon termed "antanaclasis".  The logic of the scene could be then explained by Jesus telling John that the Kingdom is indeed at hand but that it is being met with resistance.  However, if the second clause were to be interpreted in a positive sense (people press into the Kingdom), then the whole verse would be positive and Carson's solution would not be needed.  The latter option also corresponds better with the Luke parallel (Lk. 16:16).  Luke has "the Kingdom of God is being preached" instead of "the Kingdom is forcibly advancing".

Theological Upshot
The Kingdom of God is all about confronting the evil powers and taking back enemy territory.  Scripture uses martial language for a reason.  We are in a war.