Christianity, Judaism, and Islam all originated in the Middle East and spread to Europe through migration, mission, and conquest, exposing them to the same historical currents.
Monotheism, belief in afterlife, moral accountability, sacred scripture, prophetic tradition—these shared tenets create structural similarity.
Centuries of coexistence led to mutual borrowing: Christian holidays atop pagan festivals, Islamic philosophy influencing Scholasticism, Jewish thought shaping European intellectual life.
18th-century emphasis on reason, tolerance, and secular governance fostered religious pluralism, reducing doctrinal rigidity and enabling peaceful coexistence.
Together, these forces produced a European religious landscape marked more by family resemblance than radical difference.