“The union between Christ and his mystical members is firm and indissoluble. Were it so that the believer only apprehended Christ—but Christ not apprehended him, we could promise little as the stability of such a union; it might quickly be dissolved: but as the believer apprehends Christ by faith—so Christ apprehends him by his Spirit—and none shall pluck him out of his hand.
Did the child only keep hold of the nurse, it might at length grow weary, and let go its hold, and so fall away: but if the nurse has her arms about the child, it is in no hazard of falling away, even though it be not actually holding by her. So, whatever sinful intermissions may happen in the exercise of faith; yet the union remains sure, by reason of the constant indwelling of the Spirit.”
—Thomas Boston, “Mystical Union”, Human Nature in Its Fourfold State (Edinburgh: Banner of Truth, 1964)
(HT: Of First Importance)