Colossians 2:7,8 - Rooted and built up in Him

2:7

We are to be "rooted and built up in Christ" . So we both sink our roots deeper into Him, and grow as people and churches. We need to know Him better, to trust Him more, and to understand more deeply the truth of the gospel. This knowledge a not for its own sake, but in order for us to hear fruit. We are gone built up on the foundation or Christ. This is what they were taught. There was no question of just "accepting Christ" , this was only the start of a process. But this is not just hard work, rather it is to be done with thanksgiving.

2:8

Ideas matter, and people can be captivated by ideas.  There were all sorts of philosophical ideas floating around. Many of these ideas are "empty deceit" . They deceive people promising all sorts of things, but ultimately delivering nothing. These things are taught need not by Godly wisdom, but by human tradition. "According to the elemental spirits of the world, and not according to Christ". Elemental spirits could be elementary principles. I'd there could be a direct or an indirect spiritual influence.  It really doesn't matter which, the key thing is that they are not according to Christ.