A crucifix (from Latin cruci fixus meaning "(one) fixed to a cross") is a cross with a representation of Jesus' body, or corpus. It is a principal symbol of the Christian religion. It is primarily used in the Catholic Church, Anglican churches, and Eastern Orthodox churches, and it emphasizes Christ's sacrifice— his death by crucifixion, which they believe brought about the redemption of humankind.
   The Eastern Christian crucifix usually includes two additional crossbars: the shorter nameplate, to which INRI was affixed; and the shorter stipes, to which the feet were nailed, which is angled upward toward penitent thief St. Dismas (to the viewer's left) and downward toward impenitent thief Gestas (to the viewer's right). It is thus eight-pointed. The corpora of Eastern crucifixes tend to be two-dimensional icons that show Jesus as already dead, as opposed to the depictions of the still-suffering Jesus that can be found in some other Churches. Also, Eastern crucifixes have Jesus' two feet nailed side by side, rather than one atop the other, as Western crucifixes do. The crown of thorns is also generally absent in Eastern crucifixes.
   Roman Catholic, Orthodox,Coptic, Anglican and Lutheran Christians generally use the crucifix in public religious services. They believe the crucifix is in keeping with Scripture, which states that “We preach Christ crucified, unto the Jews a stumbling block, and unto the Greeks foolishness.”
   Prayer in front of a crucifix is often part of devotion for Christians, especially those worshipping in a church, and private devotion in a chapel. The person may sit, stand, or kneel in front of the crucifix, sometimes looking at it in contemplation, or merely in front of it with head bowed or eyes closed. In the Roman Catholic Mass, Anglican and Lutheran Holy Eucharist, a procession begins Mass in which a crucifix is carried forward into the church followed by lector and servers, the priest, deacon, along with some of the other items used in the service such as the Gospels and the altar candles. Eastern Christian liturgical processions also include a crucifix at the head of the procession.
   The crucifix is also considered by some to be one of the most effective means of averting or opposing demons, as stated by many exorcists, including the famous exorcist of the Vatican, Father Gabriele Amorth. In folklore it is considered to ward off vampires, incubi, succubi, and other evils.
In terms of opposition, some have used an inverted (upside-down) crucifix when showing disdain for Jesus Christ or the Catholic Church which believe in His divinity. It is not uncommon for Satanists or anti-Christian athiests alike to use such symbolism in a form of protest. Interestingly, Saint Peter was martyred by being crucified upside-down.