Paul speaks of unresponsiveness to God as if it were death. Alternate translation: "When you Colossian believers were unable to respond to God" (See: [[rc://en/ta/man/translate/figs-metaphor]])
With this metaphor Paul speaks of coming into new spiritual life as if it were coming back to life physically. (See: [[rc://en/ta/man/translate/figs-metaphor]])
You were dead on two accounts: 1) you were spiritually dead, living a life of sin against Christ and 2) you were not circumcised according to the law of Moses.