thusiastērion

This is the Bible's own word for an altar, and it is used almost exclusively for the altar of the true God, never for a pagan one. Greek-speaking Jews coined it to keep that line sharp: an ordinary Greek altar was a bomos, but the place where offerings went up to the Lord got its own term, built from the verb meaning to sacrifice. So in the New Testament the word already carries the sense of holy ground, an altar set apart for God.

In the temple there were two such altars, and the same word covers both. The great altar stood out in the open court, where animals were killed and burned; the small golden altar stood inside the sanctuary, where incense was burned. Most occurrences point to the outdoor altar of sacrifice, the one worshipers approached with their gifts and priests served day by day. The word also stretches back to the altars the faithful built long before the temple, like the one Abraham raised to offer Isaac.

The book of Revelation lifts the word into heaven. There an altar stands before God's throne: souls shelter beneath it, fire is taken from it, and it even speaks. The vision pictures the true, heavenly original of which the temple altar was only a copy.

One famous verse, in the letter to the Hebrews, says that believers in Christ have an altar of their own. What that altar is has been argued about for centuries, since the writer does not spell it out, and the possibilities range from the cross of Christ to the Lord's table.