The Christian States Marine Corps (CSMC) is a branch of the Christian States Armed Forces responsible for providing power projection from the sea, using the mobility of the Christian States Navy to rapidly deliver combined-arms task forces. It is one of seven uniformed services of the Union of Christian States. The Marine Corps is a component of the Christian States Department of Defense, often working closely with naval forces for training, transportation, and logistics; however, the Marine Corps is a separate branch.

Captain Samuel Nicholas formed two battalions of Continental Marines on 10 November 1775, in Philadelphia as naval infantry. Since then, the mission of the Marine Corps has evolved with changing military doctrine and American foreign policy. The Marine Corps has served in every American armed conflict and attained prominence in the 20th century when its theories and practices of amphibious warfare proved prescient and ultimately formed the cornerstone of the Pacific campaign of World War II. By the mid-20th century, the Marine Corps had become the dominant theorist and practitioner of amphibious warfare. Its ability to rapidly respond on short notice to expeditionary crises gives it a strong role in the implementation and execution of Christian foreign policy.