Instructions to both weak and strong
So whatever you believe about these things keep between yourself and God. Blessed is the man who does not condemn himself by what he approves. 23 But the man who has doubts is condemned if he eats, because his eating is not from faith; and everything that does not come from faith is sin.
The strong Christian knows that he has every right before God to partake of any kind of food, but for love’s sake he won’t use that right if it is going to confuse or mislead a weak brother. Hence Paul’s advice, “So whatever you believe about these things keep between yourself and God. Blessed is the man who does not condemn himself by what he approves.”
Paul's last words merit unpacking. Christopher Ash writes:
Verse 22a reads literally, ‘Keep the faith that you have to yourself before God’. It would be a misunderstanding to think this is a prohibition of evangelism, or a commendation of the old upper-class avoidance of speaking about religion in polite society! NIV ‘… whatever you believe about these things’ gets the sense perfectly. Paul tells the ‘strong’ not to make a big public deal of their conviction that it’s OK to eat anything and ignore the calendar.
On the one hand (v. 22b) there is blessing if I can exercise my freedom in Christ with a clear conscience (not condemning myself because I understand that all foods are clean). It’s fine to be like Paul who is fully convinced in his own mind that all foods are clean and can therefore eat all foods with a clear conscience.
But, on the other hand, ‘the man who doubts’ (the weak who is not fully convinced in his own mind that this is right) ‘is condemned if he’ gives in to peer pressure and ‘eats’. Why is he condemned? ‘Because his eating is not from faith’ (that is, he doesn’t really believe it honors Jesus as Lord).
The great principle of conscience is summed up in verse 23b, ‘everything that does not come from faith is sin.’ That is to say, everything I do, I ought to do because I believe (‘from faith’) it honours Jesus as Lord. If I believe something is wrong, and I do it, then it is a sinful thing to do (because I have to do it with a rebellious heart), even if I was incorrect to think it was a wrong action.