A. A sacrifice is the offering of an object by a priest to God alone, and the consuming of it to acknowledge that He is the Creator and Lord of all things.
"Sacrifice." From the very earliest history of man we find people—for example, Abel, Noe, etc.—offering up sacrifice to God; that is, taking something and offering it to God, and then destroying it to show that they believed God to be the Master of life and death, and the Supreme Lord of all things. These offerings were sometimes plants or fruits, but most frequently animals.
When men lost the knowledge of the true God and began to worship idols of wood and stone, they began or continued to offer sacrifice to these false gods. Very often, too, they sacrificed human beings to please, as they imagined, these gods. They believed there was a god for everything—a god for the ocean, a god for thunder, a god for wind, for war, etc.; and when anything happened that frightened or injured the people, they believed that some of these gods were offended, and offered up sacrifice to pacify them. They had a temple in Rome called the Pantheon, or temple of all the gods, and here they kept the idols of all the gods they could think of or know. At Athens, they were afraid of neglecting any god whom they might thus give offense, and so they had an altar for the unknown god. When St. Paul came to preach, he saw this altar to the unknown god, and told them that was the God he came to preach about. (Acts 17). He preached to them the existence of the true God, and showed them that there is only one God and not many gods.
They did not have these idols of wood and stone in their temples for the same reason that we have images in our churches, because they believed that the idols were really gods, and offered sacrifice to them, whereas we know that our images are the works of men. Near the city of Jerusalem there was a great idol named Molech, to which parents offered their infants in sacrifice. We know, too, from the history of this country that the Indians used to send a beautiful young girl in a white canoe over the falls of Niagara every year, as a sacrifice offered to the god of the falls. Even yet human sacrifices are offered up on savage islands. Sometimes certain animals were selected to be heathen gods. The people who worship idols, animals, or other things of that kind as gods are called pagans, idolaters, or heathens.
The Israelites, who worshipped the true God and offered Him sacrifices because He made known to them by revelation that they should do so, had four kinds of sacrifice. They offered one for sin, another in thanksgiving for benefits received, another as an act of worship, and another to beg God's blessing. It is just for these four ends or objects we offer up the one Christian sacrifice of the holy Mass. In the beginning the head of the family offered sacrifice—as Noe did when he came out of the Ark—but after God gave His laws to Moses He appointed priests to offer up the sacrifices. Aaron, the brother of Moses, was the first priest appointed, and after him his descendants were priests. When Our Lord came and instituted a new sacrifice He established the priesthood of the New Law, and appointed His own priests, namely, the Apostles, with St. Peter as their chief, and after them their lawfully appointed successors, the bishops of the world, with the Pope as their chief. The sacrifices of the Old Law were figures of the sacrifice of the New Law, and were to cease at its institution; and when the ancient sacrifices ceased the ancient priesthood was at an end.