What's a pacifist? Because I know the Bible says to turn your swords into something that is not used to kill.
A pacifist is someone opposed to violence for any purpose. He believes that every matter can be handled without violence. Thus a pacifist is opposed to the military and police because of their use of violence. A pacifist is against the death penalty because it is the ending of life. And he is against self-defense because it requires some form of violence.
It doesn't take long in reading the Old Testament to realize that God tells men to use some forms of violence to deal with some sins. Israel had an army that was directed by God. And in the New Testament we learn that God gave governments the authority to wield the sword (Romans 13:1-4). See: May a Christian serve in government?
In Isaiah there is a prophecy concerning the church: "He shall judge between the nations, And rebuke many people; they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war anymore" (Isaiah 2:4). The prophecy is talking about the church and should be understood in the realm of the church.
"Therefore remember that you, once Gentiles in the flesh -- who are called Uncircumcision by what is called the Circumcision made in the flesh by hands -- that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity. And He came and preached peace to you who were afar off and to those who were near. For through Him we both have access by one Spirit to the Father. Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God" (Ephesians 2:11-19).
This prophecy has been fulfilled in the church. The church draws people in from all nations. National origins no longer make a difference. People can be brethren and live in peace regardless of where they were born. Efforts put into division is now put into living in harmony and growth in the church. And in the spread of Christ's kingdom, it is not done by physical warfare. "For though we walk in the flesh, we do not war according to the flesh. For the weapons of our warfare are not carnal but mighty in God for pulling down strongholds, casting down arguments and every high thing that exalts itself against the knowledge of God, bringing every thought into captivity to the obedience of Christ" (II Corinthians 10:3-5). We don't intimidate people, we persuade people to follow Christ.