We read from Colossians 2:8-19 during our Scripture reading time because it’s actually easier than we might think to lose sight of Christ being the centerpiece.  According to that passage, you can know you are thinking correctly about this when you have power over forgiven sin by holding fast to Christ.  This brings about the growth that is from God that may not necessarily be perceptible on a day to day basis, but certainly is over the long haul.  Conversely, if this power and growth is not there, there’s probably some empty deceit being trusted in and/or a holding fast to something else besides Christ, even if it’s under the umbrella of Christianity.  Perhaps we are holding fast to a past profession of faith instead of Christ.  Perhaps we are holding fast to a religious routine view of the Christian life which does not require Christ to attain to.  Or perhaps we are holding fast to the desire to be liked by as many people as possible instead of holding fast to Christ, which has the potential to cost us relationships.  Lastly, perhaps we are holding fast to the desire to obtain a life full of circumstances that promote our comfort and earthly prosperity.  All of those options are substitutes for holding fast to Christ.
Again, we can know we are not Christ-centered in our thinking and practice when we are not experiencing power and growth from God.   We are seeing a certain version of this kind of teaching in Acts 15, where Luke depicts a threat to the gospel of the most serious nature—a false gospel, which finds its theme statement in the second half of v.1–Unless you are circumcised according to the custom of Moses, you cannot be saved.  Jewish believers had merely added Christ to their life while holding fast to their law-keeping.  This certainly represents a minimizing of Christ and would undoubtedly lead to powerless living.  Let us not mimic this deadly way of thinking brethren.