According to Strong's Concordance:
Christos : the Anointed One, Messiah, Christ Original Word : Χριστός, οῦ, ὁ Part of Speech : Noun, Masculine Transliteration : Christos Phonetic Spelling : (khris-tos') Definition : the Anointed One, Messiah, Christ Usage : Anointed One; the Messiah, the Christ.
And according to Wikipedia:
In Abrahamic religions, a messiah or messias (Hebrew: מָשִׁיחַ, romanized: māšīyaḥ; Greek: μεσσίας, messías; Arabic: مسيح, masîḥ; lit. 'the anointed one') is a saviour or liberator of a group of people. The concepts of mashiach, messianism, and of a Messianic Age originated in Judaism, and in the Hebrew Bible, in which a mashiach is a king or High Priest traditionally anointed with holy anointing oil.
The literal translation of the Hebrew word mashiach (המשיח, messiah), is 'anointed', which refers to a ritual of consecrating (dedicating for a special service) someone or something by putting holy oil upon it. It is used throughout the Hebrew Bible in reference to a wide variety of individuals and objects; for example, kings, priests and prophets, the altar in the Temple, vessels, unleavened bread, and even a non-Jewish king (Cyrus the Great).
Therefor to qualify as the Christ (Messiah), the person has to:
- be a saviour or liberator of a group of people
- a king
- a high priest
- a prophet
- anointed with oil
Jesus meet all these requirements.
According to John, one of the requirements for salvation is to confess Jesus is the Christ (1 John 2:22-23)