Romans 14:23

‘But he who doubts is condemned if he eats, because (it is) not of faith, and whatever is not of faith is sin.'

But if someone who wavers over whether it is right to eat meat, on the grounds that it may be unclean, does eat of such meat, he brings himself into condemnation. And the reason why he does so is because his act is not one carried out in joyous faith, but is one carried out fearing that it might be sinful. He is doing what he fears might be wrong. Indeed, anything that we do fearing that it might be wrong is sin, for ‘whatever is not of faith is sin.' So important is ‘not sinning' that the Christian says, ‘if I am not sure it is right I must not do it. I must only do what I know to be right', and this because of his hatred of sin and his fear lest he be defiled by it.