Moreover we must take heed that we do not, in explaining this union between Christ and believers, include more in it than what belongs to creatures infinitely below him, to whom they are said to be united: therefore we cannot but abhor the blasphemy of those who speak of an essential union of creatures with God; or, as though they had hereby something derived to them in common with Christ the great Mediator.[1] But passing by this method of accounting for the union between Christ and believers, there are two senses in which it is taken in scripture; one is, that which results from Christ’s being their federal head, representative, or surety; having undertaken to deal with the justice of God in their behalf, so that what he should do, as standing in this relation to them, should be placed to their account, as much as though it had been done by them in their own persons: this is what contains in it their concern in the covenant of grace, made with him in their behalf; of which something has been said under a foregoing answer;[2] and it is the foundation of their sins being imputed to him, and his righteousness to them; which will be farther considered, when we treat of the doctrine of justification under a following answer.[3] Therefore this union with Christ, which is mentioned in the answer we are now explaining, is of another nature, and, in some respects, may be properly styled a _vital union_, as all spiritual life is derived from it; or a _conjugal union_, as it is founded in consent, and said to be by faith. Now there are two things observed concerning it. 1. It is expressed by our being spiritually and mystically joined to Christ: it is styled a _spiritual_ union, in opposition to those gross and carnal conceptions which persons may entertain concerning things being joined together in a natural way; and, indeed, whatever respects salvation is of a spiritual nature. It is moreover called a _mystical_ union, which is the word most used by those who treat on this subject; and the reason is, because the apostle calls it _a great mystery_, Eph. v. 32. by which we are not to understand the union there is between man and wife, as contained in the similitude by which he had before illustrated this doctrine, as the Papists pretend,[4] but the union that there is between Christ and his church. And it is probably styled _a mystery_, because it could never have been known without divine revelation: and as Christ’s condescension, expressed herein, can never be sufficiently admired; so it cannot be fully comprehended by us. This is such a nearness to him, and such a display of love in him _as passeth knowledge_. However, there are some similitudes used in scripture to illustrate it. As,