Acts 11:26 calls them disciples:
“And when he had found him, he brought him to Antioch. So it was that for a whole year they assembled with the church and taught a great many people. And the disciples were first called Christians in Antioch.” (Ac 11:26 NKJV)
The idea that someone can be a Christian, a follower or disciple without being in Christ's body doesn't seem correct.
“For as we have many members in one body, but all the members do not have the same function, so we, being many, are one body in Christ, and individually members of one another.” (Ro 12:4-5 NKJV)
“Now you are the body of Christ, and members individually.” (1Co 12:27 NKJV)
“And He put all things under His feet, and gave Him to be head over all things to the church, which is His body, the fullness of Him who fills all in all.” (Eph 1:22-23 NKJV)
“For we are members of His body, of His flesh and of His bones.” (Eph 5:30 NKJV)
Of course there was Judas Iscariot, who was numbered among the disciples, but was not truly one. Likewise, there may well be church members who are hypocrites, and like Judas, are not really disciples at all. But generally, when in the New Testament the body of Christ is mentioned (other than when referring to His actual physical body), it refers to Christians, followers of the Saviour. If somebody is truly a follower of Christ, then that person is in Christ.