Two views of who the violent who take the kingdom by force are:
Matthew 11:12 says that the kingdom is for those who take the opportunity to enter the kingdom with deliberate intent and fervent zeal (Matthew 7:13–14). The word used in the original Greek, biazō, refers to using force or violence to reach a goal, like someone storming a fortress or a city.
The
violent [who] take it by force
(Matthew 11:12) are those who try to gain the kingdom wrongly. The expansion of the kingdom must occur not mainly in numbers, but rather—in addition to its new revelation—in how those who once stood outside are being drawn in. This is why Christ’s path excludes any effort to establish a purely outward kingdom or an illegitimate, violent seizing of the kingdom.
Interpretation 1:
Matthew 11:12 says that the kingdom is not for those who desire to acquire its citizenship effortlessly. The kingdom is destined for those who give their all—those who are willing to seize the opportunity to enter the kingdom of God with deliberate intent and fervent zeal (cf. Matthew 7:13–14). The word used in the original Greek, biazō, conveys the very strong meaning of using force or violence in order to reach a goal. The gates stand open for those who are determined to take possession of the kingdom. This imagery recalls someone storming a fortress or a city, sparing no effort to ensure success.1
Interpretation 2:
The violent who take it by force
(Matthew 11:12) refers to those who try to acquire the kingdom of heaven illegitimately. The powerful expansion of the kingdom of God must not be sought primarily in the large number of its citizens, but rather—in addition to its new revelation—in the fact that those who once stood farthest away have now been drawn in. This is why Christ specifically follows a path in which there can be no possibilities of a zealot who works to establish a purely outward kingdom, nor can there be any mention of an illegitimate, violent seizing of the kingdom of God2
12 From the days of John the Baptist until now the kingdom of heaven has suffered violence,and the violent take it by force.