The key to understanding Jesus' words lies in understanding how the phrase "kingdom of God" or "kingdom of heaven" is used. We know that the Kingdom of God has a future aspect, when Christ will rule over the nations and His glorified brothers and sisters will reign with Him. There is also a present aspect, as we have already been conveyed into the Kingdom (Colossians 1:13), and now our citizenship is in heaven (Philippians 3:20). We are already part of that heavenly Kingdom. It is a present reality for the firstfruits—though not in its fullness—and in the near future, it will be a worldwide reality.
Yet, there is another way to understand the Kingdom. When Jesus said that "the kingdom of heaven is at hand" (Matthew 4:17)—meaning nearby—He was referring to Himself. When He told the Pharisees that the Kingdom of God was among them, or in their midst (Luke 17:21), He referred to Himself. The king is always the highest representative of a kingdom, so when the king is present, the kingdom is also present.
We can see this in a couple of scriptures: "But if I cast out demons by the Spirit of God, surely the kingdom of God has come upon you" (Matthew 12:28). Here, God's Kingdom is defined as Jesus' exercise of His power. The King, in exerting His authority over unclean spirits, displays the reign or the rule of God. The Kingdom of God is found in the Person of Jesus Christ.
This can also be seen in Mark 9:1-2:
And He said to them, "Assuredly, I say to you that there are some standing here who will not taste death till they see the kingdom of God present with power." Now after six days Jesus took Peter, James, and John, and led them up on a high mountain apart by themselves; and He was transfigured before them.
Jesus tells them they will see the Kingdom of God present with power, and within a week they see Him transfigured. His being revealed to them in glory was a demonstration of the power of God's Kingdom. Even without the glory, what stood among them was still the Kingdom of God. Because He is the King, as the central figure of the Kingdom, wherever He went, the Kingdom was present. In the book of Acts, the message of the Kingdom is inextricably tied to the central Being in that Kingdom (Acts 8:12; 19:8-10; 28:23, 31). To take this a step further, where the King abides in any person or where a person is in Christ, the Kingdom is also present.
We can now apply this principle to Christ's statements. Matthew 11:12 says that from the days of John the Baptist's preaching until that of Jesus—and even to today—Christ and those in whom He dwells suffer violence: physical or verbal assault, affliction, oppression, constraint, and perhaps even martyrdom. This world's forceful and self-willed people "seize" that Kingdom as they would a fortified city, through opposing its citizens in some way.
Similarly, in Luke 16:16, Jesus is saying that the Kingdom of God has been preached, and everyone uses violence against it, signifying opposition in one form or another, to constrain or repress the King and His citizens. As John records, "He came to His own, and His own did not receive Him" (John 1:11).
In other words, the gospel message was not popular. It bore fruit in those who were being called (Isaiah 55:11). Others hoped that the kingdom of Judah would be restored, and they were probably content to wait and watch this Man as He went about—as curiosity-seekers rather than opponents. However, for those who had a vested interest in maintaining the political and religious status quo, the gospel was seen as a threat, and those linked with the Kingdom of Jesus Christ were the object of all manner of resistance and persecution, both before and especially after His death.
Notice, for example, Jesus' words in Matthew 23:13: "But woe to you, scribes and Pharisees, hypocrites! For you shut up the kingdom of heaven against men; for you neither go in yourselves, nor do you allow those who are entering to go in." Some were then in the process of entering the Kingdom, and the resistance and oppression of the scribes and Pharisees were obstacles to that entrance. John 9:22 records that "the Jews had agreed already that if anyone confessed that He was Christ, he would be put out of the synagogue." The scribes and Pharisees, as well as those influenced by them, persecuted those God was drawing into His Kingdom. There was such animosity that the King Himself suffered the most awful violence that has ever been perpetrated: a mob of creatures wantonly crucifying their sinless Creator.
We face a similar circumstance today. Even nominal Christians suffer Muslim persecution in one part of the world, while others are blocked, ridiculed, and constrained by secularists and humanists in another. True Christianity is denounced as being heretical and cultic, and its adherents suffer violence in various ways. This violence does not have to be physical violence. It can be verbal. It can be passive. It can be persecution or opposition in any number of ways.
Wherever the spirit of Satan is present, his children make the way difficult for those who are in Christ or who are being drawn to Him. They reject the royal law of the Kingdom and ridicule God's sovereignty. They sneer at His inspired Word. The violence that the Kingdom suffers will vary by degrees, but it is found wherever the ruler of this world has influence.
This is why Jesus says in John 16:33 that in the world, we will have persecution, but He also says to "be of good cheer." He does not say He will remove persecution right away, but instead, He says that He has overcome the world. He sets limits on how much violence He will allow, and what He does allow He will redeem for His own good will. The violence we suffer will never compare to the violence that He suffered for us. One day soon, though, the violence against the Kingdom will be defeated, and the violent will be given the opportunity to worship the King whom they have pierced (Zechariah 12:10).