"Then said one unto him, Lord, are there few that be saved? And he said unto them, strive to enter in at the strait gate: for many, I say unto you, will seek to enter in, and shall not be able." Luke 13:23, 24
IN JESUS TODAY!
The word strive or to strive is the same as fight, we must engage in a battle with evil in order to be able to enter into heaven. This evil is always present in the world, but it is a choice that we all must make regarding whether or not we will engage it in battle. When a person chooses Jesus as their Lord and Savior this is the first blow against the forces of evil and it is a firm statement to the evil in the world that you are committed to this battle. The Bible tells us to overcome evil with good, "Be not overcome of evil, but overcome evil with good." Romans 12:21
A person who is passive and would rather not engage in this battle might say to themselves, I just want to have a fun and happy life, I don't really believe like that, I will get into heaven because I do god things for other people and I don't do wrong things on purpose. The truth is this, it is not possible for someone to get into heaven without accepting Jesus as their Lord and Savior and therefore it is not possible to be passive and fail to engage in this battle and still expect to get into heaven.
"Neither is there Salvation in any other; for there is none other name under heaven given among men, whereby we must be saved." Acts 4:12 it is impossible to get to heaven without striving to enter or engaging in battle with the evil of this world.