Our Judeo-Greek New Testament (Matthew 5:13) preserves the words of Jesus to his disciples - "You are 'the salt of the land'" - τo ἅλας τῆς γῆς (pronounced as to halas teis geis). He did not say, “You are the salt of the earth,” as the phrase is popularly translated. What did he mean by that? To fully appreciate the meaning of Yeshua's words we must consider them in their native cultural context. That means we must examine His words in Hebrew as well as Greek.
The Hebrew word for “land” is אֶרֶץ (eretz). After all, the ancients did not have a concept of "the planet Earth" as we do today. When Jesus said, “you are the salt of the land,” He was referring specifically to the “Land of Israel”. In Biblical Hebrew, “salt” is מֶלַח (melach) and it is an “indestructible mineral”. That is why the idea of salt not being salty any more and yet still being called salt makes no sense. His listeners would have recognized this.
Salt was valuable. It was used as a fertilizer, as a food preservative, and as a seasoning. Salt occurs in a variety of contexts in the Hebrew Bible. For example, God makes an irrevocable “Covenant of Salt” with the House of David (2 Chron 13:5). Salt was added to sacrifices as a symbol of God’s covenant faithfulness (Lev 2:13; Ezek 43:24). Salt symbolizes purity (Ex 30:34-36) and is used in reference to Israel’s geographical boundaries (Num. 34:12; Josh 15:2). Salt can even symbolize God’s judgment and curses (Gen 19:24-26; Deut. 29:22-30). While these categories are diverse, the pervasive theme of “God’s Covenant” binds them all together in harmony.
God's "covenant of salt" with His people is tangible, permanent, and serves a specific purpose. Yeshua’s disciples share these same qualities. They are visible symbols of God’s irrevocable covenant with Israel. Their actions are compared with salt, which stops decay and corruption. They preserve Israel’s covenant by faithfully obeying God’s laws in faith. Just as the salt can purify, Yeshua’s disciples purify the world around them and make it a better place. And like salt which was added to sacrifices for symbolic emphasis, Yeshua’s disciples themselves become sacrifices. They “offer up” their own lives for the sake of the Kingdom (Matt 5:11-12). There is so much depth in the Bible, but sometimes it is hidden behind culture, customs, and unfamiliar language. Knowing this contexts is often the key to unlocking the meaning.