"But food does not bring us near to God; we are no worse if we do not eat, and no better if we do." NIV translation
We see that the greater knowledge is the fact that our actions do not bring holiness. It is Jesus' action on our behalf that brings holiness to our lives. This same principle applies to many "grey areas" in our lives. There are many who feel superior because of the fact that they do not take part in many of the things around them. These "holier than thou" people do not understand the principle that our holiness is in Christ and not in our own actions.
"Be careful, however, that the exercise of your freedom does not become a stumbling block to the weak. For if anyone with a weak conscience sees you who have this knowledge eating in an idol's temple, won't he be emboldened to eat what has been sacrificed to idols? So this weak brother, for whom Christ died, is destroyed by your knowledge." NIV translation
This liberty that we have in Christ should be limited by our love for our fellow brothers in Christ. We are free to do anything but willingly don't in order to avoid leading these brothers to do something that they feel is wrong. A more modern example is the drinking of alcohol. In Christ, I am free to enjoy a cold beer on a hot day but, because I am in Christ and know what alcohol can do to a life, I do not drink. My drinking could lead less mature Christians who struggle with a drinking problem to get drunk and to draw away from Jesus Christ.
"When you sin against your brothers in this way and wound their weak conscience, you sin against Christ. Therefore, if what I eat causes my brother to fall into sin, I will never eat meat again, so that I will not cause him to fall." NIV translation
We willingly limit our freedom in Christ for the benefit of our weaker brothers in the faith. That is the definition of love as we see in 1 John 3:16. We could also go a step further and educate the weaker brother by explaining grace and the freedom that we have because of our relationship with Jesus Christ. In doing so, we can remove some of the chains of religion that have our brothers bound and keep them from enjoying their freedom in Christ.