Differentiating obsessive-compulsive symptoms from delusional ideation in schizophrenia: a case report of psychotic relapse with religious content

Obsessive-compulsive symptoms (OCS) are common in schizophrenia and may reflect either true comorbidity or a secondary manifestation of psychosis. Distinguishing OCS from delusion-driven ideation is a major clinical challenge, particularly when phenomena are shaped by strong religious or moral themes. In individuals with deeply rooted spiritual or cultural identities, such content can blur diagnostic boundaries and reduce responsiveness to standard cognitive-behavioural interventions. We report the case of a patient with schizophrenia who, after a period of sustained remission on maintenance antipsychotic treatment, presented with a new episode of disorganized behaviour and impaired social engagement. During this episode, after a brief period of partial outpatient stabilization, religiously themed intrusive thoughts and associated compulsive behaviours emerged. After non-response to two antipsychotics, the patient was admitted for clozapine initiation together with an empirical selective serotonin reuptake inhibitor trial. Longitudinal assessment indicated that the obsessive-compulsive-like symptoms were closely linked to a delusional framework involving perceived divine testing and moral transgression. Marked clinical improvement followed, and sertraline was discontinued after sustained stabilization. During outpatient care, psychosocial intervention initially focused on Cognitive Behavioural Therapy for Psychosis (CBTp). Τhe combination of rigid religious beliefs and cognitive inflexibility was associated with limited response to standard CBTp techniques, prompting a shift to Recovery-Oriented Cognitive Therapy (CT-R) with emphasis on functional re-engagement and coping skills. Over eight months, the patient achieved meaningful functional improvement. This case illustrates the diagnostic complexity of differentiating OCS from delusional ideation in schizophrenia and shows how religiously infused content can compound diagnostic uncertainty and therapeutic resistance, necessitating an integrative, formulation-driven approach.