God over all
Whether the doxology calls Christ God or blesses God above Christ, as the punctuation decides.
Romans 9:5
5of whom are the fathers, and from whom is Christ as concerning the flesh, who is over all, God, blessed forever. Amen.
What each tradition says
Rabbinic / Midrashic
No sourced position found. Checked the Jewish Encyclopedia (1905) via jewishencyclopedia.com: 'Paul of Tarsus' (id 11952), 'Jesus of Nazareth' (8616), 'Christianity in its Relation to Judaism' (4366 — cites Rom. ix. 4, never ix. 5), 'Faith' (5982), 'Atonement' (2092), 'Atonement, Day of' (2093): none treats Romans 9:5, its punctuation, or its doxology; the JE has no running verse-commentary on Romans.
Patristic
Hilary of Poitiers states that Paul knows full well that Christ is God. He points to Paul’s words, “Whose are the fathers, and of whom is Christ, Who is God over all.” This identifies Christ as God over all.
Hilary of Poitiers, On the Trinity (NPNF2-09, ed. Schaff) — Book IX, § 37
Catholic
Ferdinand Prat reads Titus 2:13 as calling Christ “our great God and Saviour Jesus Christ,” and Romans 9:5 as calling Him “God over all things.” Prat says that by His infinite transcendency Christ effaces the sum and substance of created things.
Ferdinand Prat, St. Paul (The Catholic Encyclopedia, 1911) — Section 'Christology' — (e) 'Christ is the one Lord'
Orthodox
No sourced position found. Checked Philaret's Longer Catechism (pravoslavieto.com): no verse commentary on Romans anywhere, and the Second Article materials do not cite Rom. 9:5; The Acts and Decrees of the Synod of Jerusalem (Robertson 1899, archive.org actsdecreesofsyn00orth): Trinity/predestination decrees only, no treatment of Rom. 9:5 or its punctuation; CCEL NPNF2-09 John of Damascus, Exposition of the Orthodox Faith: Rom. ix. 5 is not cited.
Reformed / Protestant
Gill applies the doxology to Christ, describing him as over all, angels and men, their Creator, Upholder, and Governor. He has another, divine nature, being God truly and properly God, blessed forevermore.
John Gill, John Gill's Exposition of the Whole Bible, on Romans 9:5 — Exposition of Romans 9:5 (the doxology applies to Christ)
Evangelical
Albert Barnes takes "God blessed forever" in Romans 9:5 as evidently applied to the Lord Jesus. He says this proves Jesus is divine, and that if the translation is fairly made and has never been proved erroneous, it demonstrates he is God as well as man.
Albert Barnes, Albert Barnes' Bible Commentary, on Romans 9:5 — Notes on Romans 9:5 ('God blessed forever')