Union with Christ is the architecture beneath every benefit of salvation. The Greek phrase ἐν Χριστῷ — and its allied locative formulae ἐν αὐτῷ, ἐν ᾧ, and ἐν Κυρίῳ — name the location in which the believer lives, dies, rises, and is glorified. Every blessing has its address in the person of the Son.

— ἐν Χριστῷ / ἐν Χριστῷ Ἰησοῦ

The technical Pauline formula. The believer is so identified with Christ that union becomes the location of every saving benefit —

• justification (Romans 3:24; Galatians 2:17),
• regeneration and new creation (2 Corinthians 5:17; Ephesians 2:10),
• sonship (Galatians 3:26),
• sanctification (1 Corinthians 1:2),
• resurrection (1 Corinthians 15:22),
• and final glorification (1 Thessalonians 4:16).

Every Pauline letter except the shortest (Titus) uses it; Ephesians and the Pastorals are saturated with it.