See 1 Corinthians 1:11-13. Note that just as today, where denominations are often named with regard to the leader that spawned them, factions were beginning to appear in the New Testament church. Note also that Paul was appalled by it and sought to crush it even in its incipient form. Lastly, note that there were even ones who chose the name “Christ” as if they were trying to say their group was “above” the factions led by human leaders. Even this form of grouping was disallowed by Paul.