Trinity Sunday is observed worldwide in Western Christianity on the first Sunday after Pentecost, with the earliest possible date being May 17 and the latest June 20. This feast celebrates the Christian doctrine of the Trinity, which encompasses the Father, the Son, and the Holy Spirit. The observance originated in response to heresies that questioned the Trinity, leading to the establishment of a special office with canticles, responses, a preface, and hymns for Sundays. Initially ordered by Pope John XXII, it was later elevated to a primary feast by Pope Pius X, who proclaimed the doctrine of the Trinity to the world on July 24, 1911. Trinity Sunday is recognized by various denominations, including Anglican, Roman Catholic, Lutheran, Methodist, Presbyterian, and Baptist churches.