Abstract: This chapter examines the manifestations of antisemitism within three international online large groups convened by the Greek Institute of Relational and Group Psychotherapy following the October 7, 2023, attacks in Israel. Drawing on the social unconscious (Hopper, Fromm), relational psychoanalysis, and group-as-whole dynamics, the analysis traces how 80–120 mental health professionals enacted unconscious antisemitic patterns across three phases: initial idealization of the Greek cofacilitators as “neutral” containers, subsequent demonization marked by paranoid suspicion and conspiratorial attribution, and finally, fragmented empathy, where Jewish grief became conditional upon political disclaimers. The chapter introduces “conditional solidarity” as a contemporary antisemitic mechanism whereby Israeli professionals’ trauma is delegitimized unless accompanied by self-condemnation. Integrating the Talmudic Bar Kamtza narrative and the Greek Danaids myth, the analysis illuminates how institutional failures to process collective mourning perpetuate cycles of envy, aggression, and unmetabolized loss. The concept of “institutional illiteracy” describes professional communities’ inability to hold the complexity of Jewish identity, resulting in persecutory-paranoid dynamics rather than reflective containment. This psychodynamic approach reveals antisemitism’s persistence within ostensibly progressive therapeutic spaces.