1. Exposition

What was signified in the building of an altar and the writing of the law on the stones?

Joshua 8:30–32 (ESV)

30 At that time Joshua built an altar to the LORD, the God of Israel, on Mount Ebal,

In building the altar, along with using it for sacrifices, Israel was also visibly proclaiming that the land belongs to the Lord. The Lord alone is to be worshipped in the land of promise. Also, if the words of the law were written on the stones of the altar, that would also symbolically show that the law of the Lord is to be obeyed in this land.