Colossians 2:7 - rooted and built up in Him and established in the faith, as you have been taught
There are two important words here in the Scripture. One is "rooted" and the other is "built up". One comes from the agriculture mindset and the other comes from the construction mindset.
The term rooted essentially means to be fixed or to be strengthened. We create in out minds a picture of a tree standing tall and deeply rooted. As you look at a tree you must realize that it is not the branches that creates stability, it is the roots. The roots of a tree create the stability that the tree needs and provides the continual nutrients that the tree needs to sustain life. This leaves the branches to produce the fruits for reproduction.
The second picture of being "built up" gives us the image of a house or building built on its foundation. The deep and strong foundation of a house allows for a tall building that can withstand the pressures of the environment. That is the same way we as Christians are supposed to be. We need to be well rooted and built up on a strong foundation to resist the destructive nature of the world. How do we do that?
We walk in our training.
The verse we just read says "as you have been taught". God's Word here is telling us that we need to be rooted and founded in our faith as we have been taught. This is one area where the church today is experiencing difficulty. Jesus commanded us to go and make disciples, not to go and make decisions. We have to understand the process and where it ends. Jesus Himself selected 12 individuals whom he poured His life into for almost three years. We need to do the same, otherwise those who we thought we had may someday disappear.