Reasoning steps: One person, God and man

Verdicts: F4 · One person, God and man. Shared notes and post-750 development: christology.

F04.1 (was christology/X1): One person, truly God and truly man

Step F04.1.1: Scripture

John 1:14 (ὁ λόγος σὰρξ ἐγένετο); Phil 2:6–7 (in the form of God, took the form of a servant); Col 2:9 (all the fullness of deity bodily); Heb 2:17 and 4:15 (made like his brothers in every respect, without sin). One subject is both God and man throughout.

Step F04.1.2: Patristic evidence

Ignatius (T1): ‘God existing in flesh … both of Mary and of God’. Gregory: ’that which He has not assumed He has not healed’. Ephesus: Emmanuel ‘very God’, Mary Θεοτόκος. Chalcedon: ‘in two natures, unconfusedly, immutably, indivisibly, inseparably’. Severus (T4): ‘one nature of God the Word incarnate’, from Cyril, and he rejects Leo’s Tome as ‘impious’. Sources: ignatius-chr-s1 · gregory-nazianzen-chr-s1 · ephesus-chr-s1 · chalcedon-chr-s1 · severus-of-antioch-chr-s1.

Step F04.1.3: Weighing decision

On the substance (one subject, full deity, full humanity, no mixture) the witness is unanimous from T1. On the formula it splits after 451: Chalcedon’s ‘in two natures’ vs the Cyrilline ‘one incarnate nature’ kept by Severus. Both sides confess full deity and full humanity, so both are scored as close on substance; a Christ whose flesh is not taken from Mary falls outside both (Chalcedon rejects ‘heavenly or some substance other than that which was taken of us’).

• Confidence: High (substance); medium (which formula).

Step F04.1.4: Source-proximity weighing

• Scripture (benchmark): One subject is truly God (John 1:1; Col 2:9) and truly man, like us in every respect except sin (Heb 2:17; 4:15). Scripture does not settle the later nature-terminology. (Scripture confidence: high)
• Assessment: T1 Ignatius and Scripture fix the substance. The terminology dispute is T3–T4 and has no biblical decision. Menno Simons’s ‘celestial flesh’ (Christ generated ‘in Mary’, not of her substance) lacks early and biblical support, though Menno affirms true humanity.