Have some fun and ask any temple-going member of the Church why the ancient patriarchs built altars. They might say something like: in order to offer sacrifices that were supposed to point their minds towards the sacrifice of God’s Only Begotten, right? And that’s not wrong, but it’s not complete either.
They built altars as a means of talking, face to face, with God. For example, in Abraham 2:
So the part in Moses 5 about Adam being told the sacrifice was in similitude of the sacrifice of the Son was not the purpose of the sacrifice but merely an explanation of the fact that the Son is the means through which we are redeemed from the Fall, brought back into the presence of the Father and can, thereby, communicate with the Father.18 And then we passed from Jershon through the land unto the place of Sechem; it was situated in the plains of Moreh, and we had already come into the borders of the land of the Canaanites, and I offered sacrifice there in the plains of Moreh, and called on the Lord devoutly, because we had already come into the land of this idolatrous nation.
19 And the Lord appeared unto me in answer to my prayers, and said unto me: Unto thy seed will I give this land.
20 And I, Abraham, arose from the place of the altar which I had built unto the Lord, and removed from thence unto a mountain on the east of Bethel, and pitched my tent there, Bethel on the west, and Hai on the east; and there I built another altar unto the Lord, and called again upon the name of the Lord.
How does that apply today? The purpose of our altars should be the establishment of communion between the Father and the worshipper. We go through all the motions in the temple but...do we ever arrive at actual communion, as the “the fathers” did?