Four things that made the OT Altar more the than just metal or stone.
1. It was a place of active faith.
....a . Only those who believe and follow the Lord will come to such a place. It's a place where faith takes action.
2. It is a place of public statement, acknowledging their depenancy upon God.
....a . A public profession by a display of action before the congration.
3. A place that destroys self/pride and brings about humility.
4. Where the altar was, there was worship, and it revealed God was moving in there midst, to those who stood near by.
The Pictorial Encyclopedia of the bible, by Merrill C. Tenny says this about the altar. Quote "The covenant code (Exod 20:24-26) clearly recognizes a plurality of altars, implying that the object was an almost indispensable accompaniment of formal worship, and that sacrifice, which was inseparable from worship, and all forms of approach to the Deity could not be made without an altar." There could be no worship without a sacrifice and there was not sacrifice without an altar. Thus no relationship was possible without this simple but profound item.
But you say Allan, that was the Old Testament and we are under the New. We no longer need altars to sacrifice. I tell you this and listen closely. Yes, we do need these altars, and more now than ever. The Old Test. is the physical representation of the spiritual aspect (New Test) - so in relation to this let me explain:
Did you know that the altar of sacrifice was always out in the open? You could never and would never find this kind of altar inside. It was always outside for all to see that you were committing something unto the Lord. The only other altar mentioned in the Temple is the altar of incense, and it was in the Temple itself (the Holy Place) representing the prayers of the people. This is the most beautiful picture of a believer. Outwardly displaying a need but inwardly seeking the Lord. Not giving great prayers for all to hear, but being there for all to see. (Luk 18:10-14) And this will allow others to respond as the Lord leads them toward and or for us; thus we as a body can function and walk in Spirit and Truth in unity and fellowship/partnership.
There are four spiritual things in the N.T. altar, that mirror the O.T. Altar.
1. It was a place of active faith.
....a . Only those who believe and follow the Lord will come to such a place. It's a place where faith takes action. (James 2:14)
2. It is a place of public statement, acknowledging publically our dependancy on God. IOW - A public type of Profession. i.e.
....a . Salvation -Rom. 10:9,10
....b . Repentance – I John 1:9
....c . Renewal -James 4:7-10,
....d . Declaration -Mat 10:32,33
....e . Help –I Peter 5:7, James 5:16 and Gal 6:2)
(not that the above were all done at an altar but the public aspect is what I am bringing to bear, which is what the body privy to)
3. A place that destroys self and brings about humility. (Mat 16:24,24 and II Cor. 5:15)
4. Where the altar was, there was worship, and it showed God was moving in their midst (due to the sacrifice - Christ), to those who stood near by. (John 4:23,24, John 9:31, and Acts 1:8,12 + 2:1,2,41)
Both the spiritual nature and symbolism are established in that the altar is the embodiment of the nature of God. It shows judgment and wrath without mercy. (someone must pay) It also shows His everlasting grace and mercy. (He paid it for me) and lastly it displays patience and love. (He waits for me to come in line with His will)
These are just some of the reasons but I figured I would share them.
Take it or leave it. But there is nothing in scripture against it nor specifically for it, and yet God still uses this means for His ends.
It is symbolic much like we use the sybolism of the alter in marrage like brother David illistrated. The problem is when people make it out be something it has never been declared to be, mostly because either they don't use it or they don't like the sound of it. Arguments can be made for both sides, and neither are unbiblical. One might not be looked upon with favor by those who don't understand it's usage and meaning but it does not change the fact that God uses this means as much as the other.