Theissen pointed to evidence which he interpreted as Jesus’ universalizing tendencies, Jesus’ tendencies to include non-Judeans. These “liberal” (as Theissen calls them) ideas of Jesus are reflected in Jesus’ eschatological views (e.g. Mt 8:11-12), according to Theissen. In other words, Jesus opted for the inclusion, rather than annihilation, of the nations / gentiles (those from East and West, in Theissen’s interpretation) option within Judaism of the time. This reflects continuity with those Jews who likewise imagined the end-time inclusion of the Gentiles, as well as some continuity with Paul’s subsequent focus on including gentiles in God’s end-time community, according to Theissen.
I've argued similarly in my Ph.D dissertation and looked at the issue of continuity and discontinuity more specifically in a EABS paper to be published by WUNT and edited by Tom Holmen.