"From the days of John the Baptist until now the kingdom of heaven has suffered violence, and the violent take it by force." (Matt 11:2)
This is a remarkable passage about what should be our approach toward a holy life, or striving to enter heaven. I remember hearing some John Piper sermons about a "violent streak in Christianity". By that he did not mean violence against others, but violence against the part of us that would do violence to others. In other words violence and war against indwelling sin. Thomas Watson (my favorite puritan author) writes this:
“This is the first thing in holy violence: resolution of their will; I will have heaven whatever it costs me and this resolution must be in the strength of Christ.” (Thomas Watson, "Heaven Taken By Storm")
Let us strive then to enter the narrow gate.