Romans 14:23

And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin.

Cross References

Romans 13:2 Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation.
1 Corinthians 8:7 Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled.
1 Corinthians 11:29-31 For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord's body. For this cause many are weak and sickly among you, and many sleep. For if we would judge ourselves, we should not be judged.
Romans 14:5 One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind.
Titus 1:15 Unto the pure all things are pure: but unto them that are defiled and unbelieving is nothing pure; but even their mind and conscience is defiled.
Hebrews 11:6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.