The first and the last
Whether the divine predicates of the one God are given to the risen Christ, and what that makes him.
Revelation 1:17-18
17When I saw him, I fell at his feet like a dead man. He laid his right hand on me, saying, “Don’t be afraid. I am the first and the last,
18and the Living one. I was dead, and behold, I am alive forever and ever. Amen. I have the keys of Death and of Hades.
Isaiah 44:6-8
6This is what Yahweh, the King of Israel, and his Redeemer, Yahweh of Armies, says: “I am the first, and I am the last; and besides me there is no God.
7Who is like me? Who will call, and will declare it, and set it in order for me, since I established the ancient people? Let them declare the things that are coming, and that will happen.
8Don’t fear, neither be afraid. Haven’t I declared it to you long ago, and shown it? You are my witnesses. Is there a God besides me? Indeed, there is not. I don’t know any other Rock.”
What each tradition says
Rabbinic / Midrashic
God declares that, unlike a king of flesh and blood who has father and brother, with Him it is not so. He is first because He has no father, last because He has no brother, and besides Him there is no God because He has no son.
J. D. P., The Jewish Encyclopedia (1905), art. "Monotheism" — Talmudic Attitude (on Isaiah xliv. 6)
Patristic
Athanasius states that He is in that One, and First and Only, as being of that One and Only and First the Only Word and Wisdom and Radiance. He too is the First, as the Fulness of the Godhead of the First and Only, being whole and full God.
Athanasius of Alexandria (c. 296-373), Orations against the Arians, Discourse III (Nicene and Post-Nicene Fathers, ser. 2, vol. 4) — Discourse III, ch. 23, §6 (on 'I the first and I the last')
Catholic
Haydock holds that “I am the first and the last” are the words of the Son of man, or of him who represented our Savior, Christ, to St. John. He says being first and last agrees only with the true God, as the prophet Isaias applies it several times.
George Leo Haydock, George Haydock's Catholic Bible Commentary (1859) — On Revelation 1:17
Orthodox
No sourced position found. Checked CCEL NPNF2-09 (John of Damascus cites Isa. xliv. 6 only for the unity of God, Bk. I ch. V, never for the Son; Hilary's On the Trinity likewise read as Western), NPNF2-14 (The Seven Ecumenical Councils), NPNF2-07, Philaret's Longer Catechism (pravoslavieto.com) and archive.org Cyril of Alexandria vols. 1-2 — no Eastern statement applying 'I am the first, and I am the last' to the risen Christ found.
Reformed / Protestant
Matthew Henry reads these words as instruction identifying who appeared to John. He says Christ first acquaints him with his divine nature, calling himself “the first and the last.”
Matthew Henry (1662-1714), Matthew Henry's Commentary on the Whole Bible, Vol. VI (Acts to Revelation) — On Revelation 1:17
Evangelical
John Wesley takes “the first and the last” to mean the one, eternal God, who is from everlasting to everlasting. He cites Isaiah 41:4 for this identification.
John Wesley (1703-1791), John Wesley's Notes on the Bible — Notes on Revelation 1:17