This is not about your life and the writer is not fearful for his own.
The fact that we're not afraid to die is irrelevant to the issue of upholding the fifth commandment.
Killing does not become permissible if the victim is a Christian and unafraid of coming face to face with God. Furthermore, Christian duty obliges us to to protect the defenceless from those who seek to kill them.
There is no Christian duty to protect Terri.