Altar
The first altar mentioned in the Word was the one built by Noah after he came out of the ark, after being saved from the great flood. On that altar, he sacrificed clean animals to the Lord.
Mountains represent the Lord because of their height; we need to raise our thoughts above worldly things when "talking" with the Lord. An altar is a small artificial mountain. When it's used in worship, it can call to mind this raising of thought. The fire and smoke that rise from an altar are symbolically being sent to the Lord.
Most altars were made from unhewn stones. Stones represent truths. Unhewn stones - ones that have not been shaped by men - represent truths from the Word, truths that have not been adulterated.
The clean beasts to be sacrificed represent good things, charitable acts done because they are right. The clean birds represent thoughts about doctrine and actions, and about what is right. Presenting these things is an acknowledgment that we have them from the Lord, and a giving thanks to Him for them.
In the Israelitish Tabernacle, the altar of burnt offering represented the acknowledgment of good and the altar of incense that of truth. For this reason this larger altar, which was outside by the door, was made of brass which signifies natural good, while the altar of incense was made of gold, which signifies love to the Lord from whom comes truth.
Malachi 4
1
"For, behold, the day comes, it burns as a furnace; and all the proud, and all who work wickedness, will be stubble; and the day that comes will burn them up," says Yahweh of Armies, "that it shall leave them neither root nor branch.
2
But to you who fear my name shall the sun of righteousness arise with healing in its wings. You will go out, and leap like calves of the stall.
3
You shall tread down the wicked; for they will be ashes under the soles of your feet in the day that I make," says Yahweh of Armies.
4
"Remember the law of Moses my servant, which I commanded to him in Horeb for all Israel, even statutes and ordinances.
5
Behold, I will send you Elijah the prophet before the great and terrible day of Yahweh comes.
6
He will turn the hearts of the fathers to the children, and the hearts of the children to their fathers, lest I come and strike the earth with a curse."
