The acceptable year
Whether the jubilee announced is literal or figurative, and why Jesus stops mid-sentence.
Isaiah 61:1-3
1The Lord Yahweh’s Spirit is on me, because Yahweh has anointed me to preach good news to the humble. He has sent me to bind up the broken hearted, to proclaim liberty to the captives and release to those who are bound,
2to proclaim the year of Yahweh’s favor and the day of vengeance of our God, to comfort all who mourn,
3to provide for those who mourn in Zion, to give to them a garland for ashes, the oil of joy for mourning, the garment of praise for the spirit of heaviness, that they may be called trees of righteousness, the planting of Yahweh, that he may be glorified.
Luke 4:16-21
16He came to Nazareth, where he had been brought up. He entered, as was his custom, into the synagogue on the Sabbath day, and stood up to read.
17The book of the prophet Isaiah was handed to him. He opened the book, and found the place where it was written,
18“The Spirit of the Lord is on me, because he has anointed me to preach good news to the poor. He has sent me to heal the broken hearted, to proclaim release to the captives, recovering of sight to the blind, to deliver those who are crushed,
19and to proclaim the acceptable year of the Lord.”
20He closed the book, gave it back to the attendant, and sat down. The eyes of all in the synagogue were fastened on him.
21He began to tell them, “Today, this Scripture has been fulfilled in your hearing.”
What each tradition says
Rabbinic / Midrashic
Rashi identifies the acceptable year as a year of acceptance. He describes it as a year of appeasement and good will.
Rashi, Rashi on Isaiah — The Judaica Press Tanach with Rashi, trans. A. J. Rosenberg (via Sefaria) — Rashi on Isaiah 61:2 ('to proclaim ... the acceptable year')
Patristic
Irenaeus says the acceptable year of the Lord is this present time. It is the whole time from His advent to the consummation, in which those who believe Him are called by Him and become acceptable to God, and He acquires the saved as fruits.
Irenaeus, Against Heresies, Book II, ch. XXII, §2 (ANF vol. 1, ed. Roberts & Donaldson) — Book II, Ch. XXII, §2 — the 'acceptable year' is not a twelve-month year
Catholic
Haydock identifies the acceptable year as the Year of Jubilee, when the Jews would be delivered, as a figure of Christ's redemption. He takes the day of vengeance as when the Chaldeans and others perish, and all obstinate sinners at the day of judgment.
George Leo Haydock, George Haydock's Catholic Bible Commentary (1859) — Note on Isaiah 61:2 ('to proclaim the acceptable year of the LORD, and the day of vengeance')
Orthodox
Cyril says it was Christ who preached the acceptable year of the Lord, the time when the Saviour’s proclamation was made. He understands the acceptable year to mean Christ’s first coming, and the day of restitution to mean the day of judgment.
Cyril of Alexandria, Commentary upon the Gospel according to S. Luke, Part I (trans. R. Payne Smith; Oxford, 1859) — On Luke 4:19 (the acceptable year = His first coming; the day of restitution = the day of judgment)
Reformed / Protestant
Calvin says the year may allude to the Jubilee, but undoubtedly affirms that we must wait calmly and gently till it pleases God to stretch out his hand. Paul calls this year “the time of fullness.”
John Calvin, Commentary on the Book of the Prophet Isaiah, vol. 4 (trans. William Pringle; Calvin Translation Society) — Commentary on Isaiah 61:2 ('the year of the good-pleasure of Jehovah')
Evangelical
Wesley says Isaiah 61:1 may speak of the prophet, but principally refers to Christ. Christ is anointed—set apart with gifts and authority, and given power to make all effectual—so that he alone among the prophets bears the name Messiah/Christ. The prophet first describes who Christ is, then his offices.
John Wesley, Explanatory Notes upon the Old Testament — Notes on Isaiah 61:1 ('The Spirit of the Lord is upon me')