Did the Septuagint change 'sicknesses' to 'sins' in Isaiah 53:4?

Yes, and the difference is significant. The Hebrew word in Isaiah 53:4 is cholayenu (חֳלָיֵנוּ, H2483) — "our sicknesses." The root means illness, disease, physical affliction. It appears 22 times in the Hebrew Bible and never means sin. But when the Greek translators produced the Septuagint, they rendered this word as hamartias (ἁμαρτίας) — "sins." That is an interpretive choice, not a translation. The translator read physical suffering as a metaphor for moral corruption.

The Hebrew is unambiguous:

"Nevertheless, our sicknesses he bore, and our pains he carried." — Isaiah 53:4 (MT)

The Great Isaiah Scroll from Qumran (1QIsa-a), written over a century before Christ, confirms the Hebrew says "sicknesses." There's no doubt what the original text reads.

Matthew 8:17 is where this gets interesting. When Matthew quotes Isaiah 53:4, he follows the Hebrew, not the Greek:

"He took our weaknesses and bore our diseases." — Matthew 8:17

Matthew uses astheneias ("weaknesses") and nosous ("diseases") — both physical-illness words that track the Hebrew meaning. He applies this to Jesus healing people, not forgiving them. Peter, writing later (1 Peter 2:24), quotes the same passage but follows the Greek tradition's sin language and applies it to the cross.

So Matthew and Peter are both right — they're approaching the same servant-song from two angles that the Hebrew text genuinely holds together: the servant bears physical affliction and moral guilt. What's worth knowing is that the shift from "sicknesses" to "sins" was the Septuagint's interpretive move, not the original Hebrew text's. Matthew knew his Hebrew, and he wanted you to see what the Hebrew actually says.

Read the full study on Isaiah 53