An altar is a table on which sacrifices are made. Altars are common in many religions and in the Old Testament people regularly set up altars to other gods. However, there was one altar in the tabernacle, and later in the temple, which was dedicated to the worship of the One True God of Israel. This was necessary so that the people could have their sins paid for and get right with God by sacrificing an animal in their place. Since Jesus made one sacrifice of Himself to pay for the sins of all who believe in Him, there is no longer any need for an altar. (Even so many Christians do call the table, from which Holy Communion is served, an altar).
