Luke 1:6 describes Zechariah and Elizabeth, John the Baptist's parents, as 'righteous in the sight of God, observing all the Lord's commands and decrees blamelessly' -- apparently contradicting the Christian claim that Jesus alone was sinless, since Luke attributes blameless righteousness to two other, ordinary human beings.

Engage the Greek directly. The two terms in Luke 1:6, dikaios ('righteous') and amemptos ('blameless'), are stock covenantal-piety vocabulary throughout the LXX and NT describing faithful Torah-observance, external conformity to and sincere devotion toward the commandments, within a framework that assumed such 'righteous' people would still sin and needed the sacrificial system to atone for it. This is the ordinary biblical sense applied to numerous OT figures without implying literal sinlessness: Noah is 'righteous... blameless [tamim] in his generation' (Gen 6:9) yet is later shown drunk and shamed (Gen 9:20-23); Job is 'blameless and upright' (Job 1:1) yet the whole book wrestles with his limited self-knowledge and God's rebuke of his presumption (Job 38-42); Zechariah himself, within the very same chapter, doubts Gabriel's announcement and is struck mute for his unbelief (Luke 1:18-20), direct proof within Luke's own narrative that 'blameless' in 1:6 was never intended to mean 'never sinned.' By contrast, the NT's claims about Jesus use a qualitatively different, absolute vocabulary: John 8:46 (Jesus's own unanswered public challenge, 'which of you convicts me of sin?'), 2 Cor 5:21 ('he knew no sin,' hamartian ouk egno), Heb 4:15 (tested in every respect 'yet without sin,' choris hamartias), and 1 Pet 2:22 (quoting Isa 53:9, 'he committed no sin, neither was deceit found in his mouth'), a total, exhaustive, lifelong absence of even a single sinful act, categorically stronger than the covenant-faithfulness language used of Zechariah, Elizabeth, Noah, or Job. The linked Deut 30:11-14 ('the commandment is not too hard for you... it is very near you') concerns the accessibility and comprehensibility of covenant instruction, not a claim of literal moral perfection, and stands consistent with the OT's own sacrificial provisions built specifically to atone for the sins even the 'righteous' committed (Lev 4-5). The objection, not the Christian reading, is the one flattening two genuinely different senses of 'righteous' together.

The NT's christological uniqueness claim for Jesus's sinlessness is theologically load-bearing, grounding the doctrine of a spotless, substitutionary sacrifice (Heb 9:14; 1 Pet 1:19, 'like that of a lamb without blemish or defect'), precisely because the NT elsewhere freely and unremarkably describes many faithful believers as 'righteous' and 'blameless' in the ordinary covenantal sense -- Scripture's use of this vocabulary broadly while reserving the absolute, unqualified 'without sin' language exclusively for Jesus is a coherent, deliberate literary-theological pattern.