Kingdom expansion first comes about by the addition of souls; this is based on our preaching of the Gospel.
Mark 16:15-18 15And he said unto them, Go ye into all the world, and preach the gospel to every creature.
16He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
17And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;
18They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.
The signs that are listed int the verses above are the heritage of the believer according to God's plan.
God's intent for Discipleship
Mark 3:14-15 And he ordained twelve, that they should be with him, and that he might send them forth to preach,
And to have power to heal sicknesses, and to cast out devils: