If animal sacrifices were invalidated by the sacrifice of Christ on the cross, why do we still need an altar?

Prophecies of the Old Testament clearly point out to the future establishment of the altar of the New Testament: “For from the rising of the sun, even to its going down, My name shall be great among the Gentiles; in every place incense shall be offered to My name, and a pure offering …” (Mal. 1:11); and “In that day there will be an altar to the Lord in the midst of the land of Egypt … then the Lord will be known to Egypt, and the Egyptians will know the Lord in that day, and will make sacrifice and offering” (Isa. 19:19–21).

The Lord says, “Therefore if you bring your gift to the altar” (Matt. 5:24).

The Apostle Paul warned, “you cannot partake of the Lord’s table and of the table of demons” (1 Cor. 10:21).