Are believers already members of the Kingdom?
Yes. Believers are already members of the Kingdom, for Paul writes that the Father has delivered us from the power of darkness and already translated us into the Kingdom. The Kingdom is presently in glory, in the person of Christ, awaiting its future earthly manifestation.
Les explains that while Paul does not dwell as much on the Kingdom as the Old Testament and the Gospels did concerning Israel, believers are nevertheless involved in it. In Colossians 1:12-13, Paul gives thanks to the Father who prepared us to be partakers of the inheritance of the saints in light, and who has delivered us from the power of darkness and already translated us into the Kingdom. Les therefore states that we are already members of the Kingdom. He then asks where the Kingdom is tonight, and answers that it is in glory, in the person of Christ. When Christ was on earth, John the Baptist approached Israel saying the Kingdom of Heaven is at hand, because the King was at hand.