When the Jews arrived back in 54 CE they found themselves as guests in their own home to so to speak.  The old teaching of the underworld, not to mention hell in the bible, was embarrassing.  Paul in turn wrote to the gentiles in Rome with a bold reminder about many things that included their relationship to Israel (Rom. 15:15).     It was then right from the start that Paul reminds his gentile readers that the gospel is a Jewish story which includes doctrines like hell.  In Israel’s Messianic age this included the ingathering of the gentiles.  In fact, God had not turned his back on Israel as his message was for to the Jew first and then for the gentile (Rom. 1:16); but so also was his judgment (Rom. 2:9).