Why does Paul say our citizenship is in heaven?
Paul says our citizenship is in heaven because the kingdom is not now on earth; it is in heaven. At salvation, believers were translated from darkness into the kingdom of His dear Son, which is in heaven, so their citizenship is heavenly until Christ returns with the kingdom.
Les explains that the earthly kingdom promised to Abraham and Israel will not be fulfilled until Christ sets it up; the twelve apostles will sit under Christ’s throne in Jerusalem ruling the twelve tribes. But since that kingdom is not now on earth, Paul speaks of our citizenship as being in heaven. Colossians 1 shows that at salvation we were translated from darkness into the kingdom of His dear Son in heaven. When Christ returns to the earth with His kingdom, we will be with Him and come back with Him, bodily present though not in bodies of reproduction, as the angels.