Romans 14:2 introduces the weak-faith eater, providing the very scenario where acting without faith becomes sin.

Romans 14:14 states that uncleanness depends on personal conviction — reinforcing that acting against conviction is sin.

Romans 14:22 blesses those who do not condemn themselves by what they approve — opposite of sin from doubt.

Romans 14:5 applies the same principle to days: each must be fully convinced — acting without conviction is sin.

1 Corinthians 8:7 describes how a weak conscience becomes defiled when eating with doubt, directly paralleling the condemnation here.

1 Corinthians 11:29-31 links improper eating to self-judgment and divine discipline, strongly echoing the principle of eating unworthily.

Titus 1:15 ties defilement to unbelief—'to the defiled and unbelieving, nothing is pure'—underscoring the same principle that faith determines purity.

Hebrews 11:6 states that without faith it is impossible to please God, which grounds the claim here that whatever is not from faith is sin.

1 Corinthians 8:10 shows a weak conscience being emboldened to sin — another consequence of acting without faith.

Leviticus 5:17 shows that even unknowing sin brings guilt — parallel to acting without faith (doubt) being sin.