Separation from evil is God's principle of unity is the sentence on which the whole body rests, and it descends in a straight line from Darby's judgement in 1848 that assemblies are linked and that receiving from a defiled table defiles your own. The logic is unforgiving and internally consistent: if defilement is transmissible, then contact must be controlled, and any degree of contact that cannot be controlled must be eliminated. That produces both the fellowship's cohesion — a member can walk into a meeting room in any country and be at home — and its capacity to divide, since every disagreement about who is defiled is itself grounds for a new separation. The Exclusive line divided in 1881, in 1885 over F. E. Raven's teaching on the person of Christ, in 1908, in 1970 and afterwards, and several small connexions descended from those divisions still exist alongside the PBCC.