God's gathering of people into His Anointed is as invisible as the working of His Spirit, as the coming and going of the wind. The assembly of God is something around which you cannot put boundaries. It is as pervasive as God in the world, and can only be told apart by its love, for God is love.
His Holy Spirit has put His seal on us--has marked us as His own; but that seal cannot be seen with the physical eye, nor can it be given by men. It is God's own seal . . . a spiritual seal, for God is spirit.