Simul iustus et peccator captures the paradox that Reformed and Lutheran theology affirms at the center of the Christian life. The believer stands before God as perfectly righteous — not because they have achieved righteousness, but because Christ's righteousness has been imputed (credited) to them by faith (Romans 4:5; 2 Corinthians 5:21). Simultaneously, the same believer remains truly a sinner in themselves — not fictionally or theoretically, but actually still struggling with indwelling sin (Romans 7:18–25; 1 John 1:8).
This is not a contradiction but a description of two different standings: coram Deo (before God) — the believer is iustus, declared righteous in Christ; in se (in themselves) — the believer is peccator, still marked by sin in their own nature. Justification is complete and perfect; sanctification is real but incomplete. The Christian is not partially righteous — they are fully righteous in Christ, and still a sinner in the flesh.
Luther used this phrase to protect both the objectivity of grace (it does not depend on your progress) and the humility of the Christian (you are never beyond the need for the Gospel). A church that forgets simul either falls into moral complacency (I'm righteous, I don't need to fight sin) or crushing legalism (I'm still a sinner, so I must not truly be saved).
Webster 1828 did not include this Latin phrase, but defined the component terms clearly. JUST — "righteous; upright; conforming exactly to the laws, and to principles of rectitude in social conduct." SINNER — "one that has voluntarily violated the divine law; a transgressor of the divine commands." Webster's definitions underscore the paradox: the same person who has violated God's law stands declared conforming to it — not by their own acts, but by imputation of another's righteousness. This is the scandal and the glory of grace.
• Romans 4:5 — "To the one who does not work but trusts God who justifies the ungodly, their faith is credited as righteousness."
• Romans 7:18–25 — "I know that good itself does not dwell in me, that is, in my sinful nature… Who will rescue me from this body that is subject to death? Thanks be to God, who delivers me through Jesus Christ our Lord!"
• 2 Corinthians 5:21 — "God made him who had no sin to be sin for us, so that in him we might become the righteousness of God."
• 1 John 1:8–9 — "If we claim to be without sin, we deceive ourselves… If we confess our sins, he is faithful and just and will forgive us."
• Galatians 2:20 — "I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God."
Martin Luther, Lectures on Galatians (1535):
"The saints are intrinsically always sinners — therefore they
are always extrinsically justified. The hypocrites are
intrinsically always righteous — therefore they are always
extrinsically sinners."
The distinction is key:
INTRINSIC (in se) — what you are in yourself: still a sinner
EXTRINSIC (coram Deo) — what you are in Christ: fully righteous
Luther's formula protects against two errors:
1. ANTINOMIANISM: "I'm justified, so sin doesn't matter."
→ Wrong. You are still peccator — fight sin.
2. LEGALISM: "I'm still sinning, so I must not be truly saved."
→ Wrong. You are fully iustus in Christ — rest in grace.
Reformed theology (Calvin, Westminster) agrees on the substance
while using "definitive/progressive sanctification" language.
Rome rejected the formula: Council of Trent (1547) held that
the justified sinner is not simultaneously a sinner in the same
sense — justification inherently changes the inner person.
The Reformation held this is to confuse justification (declared)
with sanctification (imparted).
The phrase has been misused in two directions. Progressive theology sometimes employs it as a license for moral complacency: "We're all simul, so don't judge." This strips the formula of its tension — Luther never meant "righteousness and sin are both fine." The peccator side is a call to humility and ongoing mortification, not a permission slip. Conversely, perfectionist traditions (certain holiness movements, Word of Faith theology) effectively deny the peccator side, claiming that true Christians can and should arrive at complete sinlessness in this life — a position that makes 1 John 1:8 ("if we say we have no sin, we deceive ourselves") inapplicable to Spirit-filled believers. Both errors destroy the pastoral power of the phrase, which is precisely to hold righteousness and remaining struggle together without collapsing either one.
• "The Gospel is for simul people — not for those who have cleaned themselves up, and not for those who have stopped fighting. For those who are both at once."
• "Your righteousness before God does not fluctuate with your performance. It is anchored in Christ — fixed, perfect, complete. Your growth in holiness is real — but it does not add to your standing."
• "Luther's formula is pastoral gold: it keeps the Christian from despair (you are iustus in Christ) and from complacency (you are still peccator — fight!)."
• "Every honest Christian confesses the simul every day: 'I am not what I should be. I am not what I will be. But I am not what I was — and today, I am clothed in Christ.'"