Jamieson, Fausset and Brown on Isaiah 53:6

6. Penitent confession of believers and of Israel in the last days (Zec 12:10).

sheep ... astray--(Psa 119:176; 1Pe 2:25). The antithesis is, "In ourselves we were scattered; in Christ we are collected together; by nature we wander, driven headlong to destruction; in Christ we find the way to the gate of life" [Calvin]. True, also, literally of Israel before its coming restoration (Eze 34:5, 6; Zec 10:2, 6; compare with Eze 34:23, 24; Jr 23:4, 5; also Mt 9:36).

laid--"hath made to light on Him" [Lowth]. Rather, "hath made to rush upon Him" [Maurer].

the iniquity--that is, its penalty; or rather, as in 2Co 5:21; He was not merely a sin offering (which would destroy the antithesis to "righteousness"), but "sin for us"; sin itself vicariously; the representative of the aggregate sin of all mankind; not sins in the plural, for the "sin" of the world is one (Ro 5:16, 17); thus we are made not merely righteous, but righteousness, even "the righteousness of God." The innocent was punished as if guilty, that the guilty might be rewarded as if innocent. This verse could be said of no mere martyr.