3. The saints’ perseverance in grace may be farther proved from their inseparable union with Christ: this union is not only federal, as he is the head of the covenant of grace, and they his members, whose salvation he has engaged to bring about, as was observed under the last head; but he may be considered also as their vital head, from whom they receive spiritual life and influence; so that as long as they abide in him, their spiritual life is maintained as derived from him: if we consider the church, or the whole election of grace as united to him, it is called, _His body_, Col. i. 24. _the fulness of him that filleth all in all_, Eph. i. 23. and every believer being a member of this body, or a part, if I may so express it, of this fulness, if it should perish and be separated from him, his body would be defective, and he would sustain a loss of that which is an ingredient in his fulness. Moreover, as this union includes in it that relation between Christ and his people, which is, by a metaphorical way of speaking, styled conjugal;[87] and accordingly is mutual, as the result of his becoming theirs by an act of grace, and they his by an act of self-dedication; this is the foundation of mutual love, which is abiding, it is certainly so on his part; because it is unchangeable, as founded on a covenant-engagement, which he cannot violate; and though their love to him be in itself subject to change, through the prevalency of corrupt nature, which too much inclines them to be unstedfast in this marriage-covenant; yet he will recover and bring them back to him, and will not deal with them as persons do with strangers, whom they exclude from their presence or favour, if they render themselves unworthy of it; but they who stand in a nearer relation to him, and accordingly are the objects of his special love, shall not be cast off for ever, how much soever he may resent their unworthy behaviour to him. Not to be separate from Christ, is, according to the apostle’s expression, not to _be separated_ from his love; and this, he says, he was _persuaded_ that he should not be, or _that neither death nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, nor height, nor depth, nor any other creature shall be able to do it_, Rom. viii. 35, 38, 39. Accordingly it is said, that _having loved his own, which were in the world, he loved them unto the end_, John xiii. 1.