Video Notes: 

• We tend to think of sin as an act someone does which leads to the idea that the act is either always sinful or always good. Certainly, there are acts like that, but there are also actions which are sinful or not depending on the situation or context.
• Something is sinful if it’s not done from faith. In other words, the “stronger” Christian here has faith that God has made all food clean. If the “weaker” Christian does not believe this, but still eats the food he considers unclean, he is sinning. He is sinning because he is not acting in faith. He is sinning because he believes he is sinning.
• It is also sinful to force someone to violate their conscience by doing the act you know is free to be done and it is sinful to cause the weaker Christian to stumble and slander you by doing the things you are free to do but they think you aren’t in front of them. Romans even warns that you may destroy their faith altogether.
• So, anything done apart from faith is sin. This, by the way, is also why even the “good” deeds of non-Christians are still sinful. Even though the act, itself, may be generally good, it is not done from faith.