Colossians 2:16-17

Therefore let no one pass judgment on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath. These are a shadow of the things to come, but the substance belongs to Christ.

-Colossians 2:16-17

Since this verse begins with "Therefore", we need to figure out what that means.  I'm assuming that it's referring to the believer's relation to Christ in the last few verses.  Those verses were talking about how we are filled in him, circumcised in him, buried with him, raised with him and made alive together with him.  Because we are so rooted and connected to Christ, "let no one pass judgment on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath".  I don't think that Paul means to say that these things (food or drink, festival, new moon, or Sabbath) are bad things.  But he's saying that these things shouldn't be a point of judgment.  So, you shouldn't let anyone accuse you of erring because you "sinned" by not obeying the Sabbath.  It can also go the other way.  You shouldn't let anyone accuse you of "sinning" by attending and participating in a particular festival.  I think the judgment can go either way, judging you for adhering to something or not adhering to something.  Regardless, you shouldn't let that happen.  Now, I realize that the way I put it was wrong too.  I don't think you can keep it from happening and that's not what Paul means.  People are going to judge you or they're not going to judge you.  Instead, I think Paul means that you shouldn't take those kinds of accusations seriously.  Or rather, you shouldn't think that their judgement of you is correct when they judge you regarding these things (food and drink, festival, new moon, or Sabbath).  Why?  Well, Paul explains in verse 17.

These are a shadow of the things to come, but the substance belongs to Christ.

For these rules are only shadows of the reality yet to come. And Christ himself is that reality. (NLT)

Such things are only a shadow of what is to come and they have only symbolic value; but the substance [the reality of what is foreshadowed] belongs to Christ. (AMP)

We shouldn't let others judge us with regards to these things because they are just a shadow and the real substance to them belongs to Christ.  I think that this means that people are judging you on the surface level with regards to these things.  They are judging you because of the Sabbath or a new moon, but not because of the heart issue of Christ.  Sure, these things can be good and can point us to Christ (I assume).  In NLT we see it say "these rules are only shadows of the reality yet to come".  First of all, they're just rules.  Secondly, it's a shadow of the reality.  I guess they're meant to point us towards Christ, but they themselves are just shadows and not the reality (Christ).  AMP tells us "they only have symbolic value".  This is why I don't think that they're necessarily bad.  They do have value, and it's symbolic.  But that also means that they're not the end all be all.  Most importantly, "the substance belongs to Christ".  You are in Christ, rooted in him and walking in him, and that is what matters.  Perhaps a new moon or a Sabbath is good and helpful because it does have symbolic value, or perhaps it is not helpful.  Most importantly is that the substance belongs to Christ.

Things like the Sabbath can be a touchy subject.  I know some people make it a point not to do any work on the Sabbath and many others are less strict.  I'm not sure, but maybe this is even like people attending church every Sunday or not.  Some may be more strict or some may be less strict about this.  This is probably the reason why I'm not quick to judge someone who doesn't go to Church every week, or someone who does work on the Sabbath.  To be fair, these things may be something of a concern, but not enough to judge.  Instead, perhaps something to encourage or talk about to our brothers and sisters in Christ.  I think another one may be pork or certain diets.  I've heard some speak strongly against eating Pork or some strongly promoting the Daniel Diet.  Sure, you can or you don't have to, it's not a big deal I guess.  More importantly, the substance belongs to Christ.  It's all about Christ.  Be rooted in him and walk in him.