I read through a few chapters of Exodus last night including chapter 20 which covers altars, and then the section in chapter 27 covering the instructions for how the altar in the tabernacle should look. There is a pretty stark contrast between the two descriptions.
Exodus 20:24-26 (NIV)
24 “‘Make an altar of earth for me and sacrifice on it your burnt offerings and fellowship offerings, your sheep and goats and your cattle. Wherever I cause my name to be honored, I will come to you and bless you. 25 If you make an altar of stones for me, do not build it with dressed stones, for you will defile it if you use a tool on it.26 And do not go up to my altar on steps, or your nakedness may be exposed.’
Here the Lord describes how an altar should be made wherever he causes his name to be honoured.
It should be made of earth or stones, and if it is made of stones, don’t use a tool or dressed stones. In other words, it’s very simple, it shouldn’t be elaborate, it’s just materials found right where the Lord has caused his name to be honoured. Lastly, it shouldn’t require them to go up on steps to it. So, it shouldn’t be raised up.
This is quite different to the elaborate altar described in chapter 27, and extremely different to the temple altar built later by Solomon.
The way I understand this is that there should be no way for an altar itself built by an individual to distract from the worship of God and the giving of sacrifices. It’s not about the altar, it’s about the person involved and God. If the altar is fancy or raised up, there is a greater risk of it becoming an idol itself. In the tabernacle and later in the temple there are priests and Levites to assist in the worship services and with sacrifices to ensure everything is done appropriately and correctly, so her God allows for the elaborateness he deserves. For an individual, on their own, building their own altar, this is unnecessary and potentially detrimental. This description very closely fits the altars described as being built regularly by Abraham, Isaac and Jacob throughout their journeys.