The Greek noun antallagma (ἀντάλλαγμα) means that which is given in exchange, an equivalent, a ransom price. It appears twice in the New Testament, both times in Jesus's rhetorical question about the soul's infinite worth: "What will a man give in exchange for his soul?" (Matthew 16:26; Mark 8:37).
Jesus's question — "What can a man give in exchange (antallagma) for his soul?" — is perhaps the most searching question in Scripture. The implied answer is: nothing. The entire material universe, every kingdom, every pleasure — none of it equals the worth of one human soul. The context is Jesus's call to cross-bearing: gain the whole world, lose your soul — net loss. The word antallagma comes from commerce and exchange. Jesus applies commercial logic to eternity: no trade is worth it. No amount of worldly gain compensates for eternal loss. Conversely, giving up everything for Christ — family, reputation, comfort — is the only exchange that yields infinite return (Matthew 19:29).