εὐαγγέλιον θεοῦ: "the gospel of God"

Says The gospel is "of God" (1:1) and "concerning his Son" (περὶ τοῦ υἱοῦ αὐτοῦ, 1:3). God promised it beforehand through his prophets in holy Scriptures (1:2). In 1:9 it is "the gospel of his Son." In 1:16 it is "God's power for salvation to everyone who believes."

Implies In 1:1 θεοῦ is best taken as a genitive of source: the good news comes from God. Its content is the Son (1:3–4). These are two aspects of one message, not two gospels.

Implies The background is the LXX's "bringing good news" (εὐαγγελίζομαι) of God's reign and return to Zion (Isa 40:9; 52:7). Paul quotes Isa 52:7 at Rom 10:15.

Uncertain Imperial "good news" language (accession, victories) makes a plausible secondary contrast, but Romans does not draw it explicitly.