What it is:
The altar is the table upon which the SACRIFICE OF THE MASS is performed. At the consecration of a church, at least one fixed altar must be consecrated. The altar is consecrated by the bishop of the diocese. An altar may be consecrated any day of the year, but a Sunday or feast day is preferable.
On the evening before the consecration, the ceremonies of the exposition of the RELICS are performed. The following day these relics will be put into a container (sepulchre), and inserted into a cavity within the altar. According to the Catholic Encyclopedia, "When the relics have been carried to the church, the consecrator anoints with holy chrism, at the four corners, the sepulchre of the altar, in which the relics are to be enclosed, thereby sanctifying the cavity in which the venerated remains of the martyrs are to rest, and then reverently places therein the case containing the relics and incenses them. Having anointed with holy chrism the nether side of the small slab that is to cover the sepulchre, he spreads blessed cement over the ledge of the sepulchre on the inside and fits the slab into the cavity, after which he anoints the upper side of the slab and the altar-table near it. He then incenses the altar...". The ceremony continues with the anointing of the altar with various oils. Then incense sticks are blessed and sprinkled with HOLY WATER. The incense is placed upon the altar in the shape of five crosses, covered with wax tapers, and burned. Finally, the bishop traces crosses on the altar with holy oil, blesses the altar cloths, vases and ornaments of the altar. The altar is now consecrated and the mass is celebrated.
How it came about:
There was no specific ceremony for the consecration of altars until the eighth century. However, in the fourth century the solemn transfer of the relics of a martyr to the altar was performed by St. Ambrose. In 386, Ambrose had built a basilica at Milan. The people asked Ambrose to consecrate the basilica, and he agreed to do so if he could obtain appropriate relics. In a dream he was shown the place that the relics could be found. He ordered excavations at a local cemetery, and the remains of Sts. Gervasius and Protasius were discovered. Many miracles were purported to have occurred at the basilica.
The ceremony of consecration developed from two directions. In the Roman ritual, the consecration took the form of a funeral liturgy, as is fitting for the "second solemn interment" of the saint’s body. The Gallican liturgy of consecration, on the other hand, took the form of the administration of BAPTISM and CONFIRMATION - with its use of water and oil.
Why it is wrong:
1) ...because human bones were used to desecrate altars, not consecrate them in the OT Scriptures,
2) ...because the veneration of relics is idolatrous,
3) ...because the altar is an abuse of the Lord’s Supper, which was a real meal among Christians, not a "real sacrifice" of the Lord Jesus Christ on an altar.
4) ...because the sepulchre is a means of "provoking the Lord to jealousy"
Warnings from Scripture:
"Now when Josiah turned, he saw the graves that were there on the mountain, and he sent and took the bones from the graves and burned them on the altar and defiled it according to the word of the Lord" 2 Kings 23:16
"And if you make an altar of stones for Me, you shall not build it out of cut stones, for if you wield your tool on it, you will profane it." Exodus 20:25
"He [King Hezekiah] removed the high places and broke down the sacred pillars and cut down the Asherah. He also broke in pieces the bronze serpent that Moses had made, for until those days the sons of Israel burned incense to it." 2 Kgs 18:4
"No, but I say that the things which the Gentiles sacrifice, they sacrifice to demons, and not to God; and I do not want you to become sharers in demons. You cannot drink the cup of the Lord and the cup of demons; you cannot partake of the table of the Lord and the table of demons. Or do we provoke the Lord to jealousy? We are not stronger than He, are we?" 1 Cor10:21-22.