what does sacrifice mean?

Today many Christians remember the martyrdom of Ignatius of Antioch, martyred on this date in the year 107. I don't check the Book of Common Prayer Lectionary all that regularly, but reading this account I was moved by the way Ignatius speaks about Jesus and particularly by the way he turns death on its head. Martyrdom exists somewhere above my comprehension; I don't think most of us in post-Christendom have been willing or able to take it in. I hesitate to post this because I don't want to come across as too heavy, but that feeling makes me wonder why I'm inhibited about asking questions like, "What does it mean to belong to God?"
So here's what one disciple's devotion sounded like. Ignatius writes:

"I am God's wheat, ground fine by the lion's teeth to be made purest bread for Christ.

No earthly pleasures, no kingdoms of this world can benefit me in any way. I prefer death in Christ Jesus to power over the farthest limits of the earth. He who died in place of us is the one object of my quest. He who rose for our sakes is my one desire. The time for my birth is close at hand. Forgive me, my brothers. Do not stand in the way of my birth to real life; do not wish me stillborn. My desire is to belong to God. Do not, then, hand me back to the world. Do not try to tempt me with material things. Let me attain pure light. Only on my arrival there can I be fully a human being. Give me the privilege of imitating the passion of my God."

from http://www.satucket.com/lectionary/Ignatius_Antioch.htm