How can Jesus be both God and human?

Christian doctrine holds that Jesus has two complete natures—fully divine and fully human—united in one single person, without either nature being diminished, mixed together, or divided into two separate individuals.

This was formally defined at the Council of Chalcedon in 451. The council described the union as existing "without confusion, without change, without division, without separation." That careful, almost defensive wording exists because the church had already rejected several simpler-sounding alternatives: one that reduced Jesus' humanity to an illusion, one that mixed the two natures into something that was neither fully God nor fully human, and one that split Jesus into two separate persons loosely cooperating.

Not every historic Christian community accepted Chalcedon's exact wording—the Oriental Orthodox churches use "miaphysite" language instead, emphasizing Christ's single united nature. Both sides reject the same errors and share far more theological common ground than the centuries-old division might suggest.