Christotokos is simply a Greek word that means “Christ-bearer” and is a title that is applied to Mary as the one who bore Christ in her womb. Mary gave birth to Christ, so Christotokos is an accurate term to describe her. However, there is a lot of history behind the term, and its usage has implications.
Nestorius, a theologian in the 5th century, taught that Mary only gave birth to the man Jesus; that is, she carried in her womb the human nature of Christ but not the divine nature. Up until this time, the term theotokos (“God-bearer”) had come into use to describe Mary. The thrust of the term was to emphasize that the baby in the womb actually was God in the flesh. The Council of Ephesus (AD 431) rejected the Nestorian doctrine and affirmed that theotokos was an appropriate description for Mary, as the unborn Jesus was fully God. However, those who reject the results of the Council of Ephesus continued to use the term Christotokos.
Christotokos is certainly accurate as far as it goes, as is the statement “Jesus is fully human.” However, the New Testament teaches that Jesus was both fully human and fully divine. (See John 1:1, 14 and our article on the deity of Christ.) Therefore, the term theotokos (“God-bearer”) is perhaps a more accurate term to describe Mary. However, that term comes with its own baggage. While theotokos does place an appropriate emphasis on the deity of the unborn Jesus, it has also been used to elevate Mary to a place that is inappropriate. Because Mary is the theotokos, the mother of Jesus who is God, some began to call her “Mother of God.” If “Mother of God” is being used to tell us something about Jesus, then it may be appropriate. If it is used to elevate Mary, then it is inappropriate.
In the final analysis, both of the terms Christotokos and theotokos are accurate, but the context in which they are used will dictate whether or not it is appropriate to use them—as is the case with many other terms.