Will there be unbelievers in the Kingdom?
The context states that it flies in the face of what we understand, that there would be no unbelievers going into the Kingdom. This understanding was based on the Old Testament program before Israel rejected the King and the Kingdom. So no, there will be no unbelievers in the Kingdom.
Les explains that according to the Old Testament program, after Israel had the King and the Kingdom, they could carry out all the promises of taking the knowledge of salvation to the Gentiles. This flew in the face of the understanding that there would be no unbelievers going into the Kingdom. However, that changed when Israel rejected the King and the Kingdom, and Jesus was crucified, went back to heaven, not to immediately come after the Tribulation, but now to wait 2,000 years while Israel has been set aside and we've had the Church Age. This was not revealed in the Old Testament; it was part of the secret.