牲 sacrificial victim

When you sacrifice the life of the cow, remember to SAY a prayer.

a sacrifice ★☆☆☆☆
犠 (sacrifice) + 牲 (sacrificial victim) = 犠牲 (a sacrifice)

a sacrifice - not only religion. You can sacrifice your happiness for someone else. If a bunch of people die in a train wreck, you can use 犠牲。

martyr ☆☆☆☆☆
犠牲 (a sacrifice) + 者 (professional) = 犠牲者 ( martyr)

a victim, a martyr