A faith that dangles in space by itself, in isolation from the rest of life, is gnostic, not Christian. See Eph. 2:10 for the why of our salvation.
Fulfilling the Great Commission is a task not in any sense "isolated", but it is personalistic, since abstractions and institutions are not Jesus' interests at all.
In fact, the tendency to disdain any object of concern other than the individual person is just about the defining element of Jesus' personality -- as depicted in the words of the canonical text, not the one we wish we had.
As an aside, I think you wanted to call me a docetic, not a gnostic. Gnostics were often un-isolated, to a fault.