That is a misconception within Christianity - just because we are peaceful it does not mean we let other religions come in and kill us, its like being in the Army we don’t go out to start the war but if someone comes in to kill us its our moral duty to protect ourselves and do what is necessary. Where does it say in the Bible that we have to let ourselves be killed.
Self-defence here is defined as “protecting oneself from injury at the hand of others.” Self-defence is not about taking vengeance. Self-defence is not about punishing criminals. Self-defence involves preserving one’s own health and life when it is threatened by the actions of others. When we speak about using potentially lethal force in self-defence, we’re talking about using weapons to protect ourselves and others, even if the weapons used could kill the attacker.
We begin by first looking at the Biblical obligation to preserve life. The Bible clearly teaches that we must preserve life–our own lives and the lives of other people. 1 Corinthians 6:19f teaches that our bodies are not our own. Rather, our bodies belong to God. Our bodies are His property and so we are not permitted to treat or destroy them as we please:
An attack on man is an attack on the image of God. At a trivial level, you’re messing with sculptures in God’s art studio. In God’s view of bloodshed, it is not merely a physiological event, but it is an assault on the divine image. Why is murder punishable by death? It says, "For in the image of God made He man
1 Chronicles 28:3 "But God said to me, ‘You shall not build a house for My name, because you have been a man of war and have shed blood.’
Proverbs 24:11 Deliver those who are drawn toward death, And hold back those stumbling to the slaughter.
Ezekiel 33 is a well-known passage:
Ezekiel 33 "… 6 ‘But if the watchman sees the sword coming and does not blow the trumpet, and the people are not warned, and a sword comes and takes a person from them, he is taken away in his iniquity; but his blood I will require from the watchman’s hand.’