Why does the tabernacle have horns? There are numerous references to horns, both in the construction and in the use of the altars (both the copper and the gold), e.g.
Make its horns on the four corners, the horns to be of one piece with it; and overlay it with copper.
You shall make an altar for burning incense; make it of acacia wood. It shall be a cubit long and a cubit wide—it shall be square—and two cubits high, its horns of one piece with it.
The Hebrew word for “horns” in these verses is specific, and it is distinct from the word, for example, for a shofar. The Hebrew word used in these verses is keren. What does it mean in the text?
The first use of keren is at the Binding of Isaac:
When Abraham looked up, his eye fell upon a ram, caught in the thicket by its horns (keren). So Abraham went and took the ram and offered it up as a burnt offering in place of his son.
Which answers the question neatly: the horns are the reason the animal is there – to provide us with a substitute sacrifice instead of our children or ourselves. And this is at the core of the concept of making a sacrifice: it is how we invest something in coming closer to G-d.
Which in turn reminds us that the sacrifice of that ram was the prototype for the altar in the temple: the horns are a common ingredient for both. If, when we offer a sacrifice on the altar, we are reminded of Abraham almost sacrificing his son, the meaning becomes deeper and more sobering.
There is a parallel elsewhere, too: the word for “horns” is found describing Moses after he came down from the mountain.
וַיְהִ֗י בְּרֶ֤דֶת מֹשֶׁה֙ מֵהַ֣ר סִינַ֔י וּשְׁנֵ֨י לֻחֹ֤ת הָֽעֵדֻת֙ בְּיַד־מֹשֶׁ֔ה בְּרִדְתּ֖וֹ מִן־הָהָ֑ר וּמֹשֶׁ֣ה לֹֽא־יָדַ֗ע כִּ֥י קָרַ֛ן ע֥וֹר פָּנָ֖יו בְּדַבְּר֥וֹ אִתּֽוֹ׃
So Moses came down from Mount Sinai. And as Moses came down from the mountain bearing the two tablets of the Pact, Moses did not know that horns were on the skin of his face, since he had spoken with God.
The first ram offered had horns. Moses was, like the horned ram, caught and committed to the service of connecting man and G-d for the rest of his days.