Texas Christian University (TCU) is affiliated with the Disciples of Christ Christian denomination, but it is a private, non-sectarian university that welcomes students of all faiths. While it has historical ties to the Christian Church (Disciples of Christ), it is not a religious institution and promotes religious diversity and tolerance on campus.

The Disciples of Christ denomination is officially named the Christian Church. The older name in parentheses is added to identify the Christian Church with a specific denomination; and many people are familiar with this particular denomination by its older name.

Mary Louis Evans has written:

'Historical sketch of the North Middletown Christian Church (Disciples of Christ), North Middletown, Kentucky, 1833-1983' -- subject(s): Church history, North Middletown Christian Church (Disciples of Christ)

If you mean all Christians worldwide, about 2 billion.

If you mean the Christian Church (Disciples of Christ) denomination, 722,823 (as of 2005).

--from Wikipedia

The Disciples of Christ are Christian, from the Protestant branch of Christianity. Jewish people generally do not believe that "Christ" has come yet, and those people who do believe he came are called Christians (followers of Jesus Christ). So, the Disciples of Christ would be gentiles, since they are not Jews.

It is worth noting that "Disciples of Christ" is the name of a particular church, not a general term for those who follow Christ.