Union with Christ is a spiritual union, not one merely that is declared or imputed, such as justification. Mystical, real, and spiritual union with the Lord Jesus occurs when one is “in Christ.”
Thomas Manton began his exposition of Romans 8 by telling his hearers “what condemnation importeth.” The world stands under condemnation because of sin—that black backdrop has made this chapter’s “No condemnation!” all the more precious to the believer. Manton next turns the reader’s attention to union with Christ as the means by which “exemption from condemnation” occurs in the life of the sinner. The sinner becomes a saint through union with Christ.
Extolling the benefits of “no condemnation,” Manton reminds his hearers that these benefits are only for those who are in union with Christ. “This privilege is the portion of those that are in Christ (Works of Thomas Manton, 11.388).” The Westminster Shorter Catechism, written by the Westminster assembly, of which Manton was a clerk, wrote, “How doth the Spirit apply to us the redemption purchased by Christ?” The answer they gave is, “The Spirit applies to us the redemption purchased by Christ, by working faith in us, and thereby uniting us to Christ in our effectual calling (WSC, 30).” Manton knew that union with Christ was central to the benefits described in this chapter.
Confusion over union with Christ is not new to our day. Hearing objections and disagreements over how this union occurs became common in the theological milieu of Manton’s social context. Manton said,
I shall here show you what it is to be in Christ…the phrase noteth union with him. There is certainly a real, but spiritual union between Christ and his members… But late cavils make it necessary to speak a little more to that argument (The Works of Manton, 11.389).
“Real” and “spiritual” union is central to the relationship with Christ in the union theology of Thomas Manton, but these ideas were pushed against in his time. “Late cavils” references current disruptions and objections to biblical truth surrounding the doctrine of union with Christ. Manton described the greatest of these cavils as those propounding “political” union.
According to Manton, union with Christ “is more than a relation to Christ as a political head.” Manton was not the only one concerned about the “late cavil” of political union. John Owen, a colleague of Manton’s in the chaplaincy of Cromwell, also saw political union as a threat to the union with Christ taught in Scripture. Owen wrote:
That there is such a union between Christ and believers is the faith of the catholic church, and has been so in all ages. Those who seem in our days to deny it, or question it, either know not what they say, or their minds are influenced by their doctrine who deny the divine persons of the Son and of the Spirit. Upon supposition of this union, reason will grant the imputation pleaded for to be reasonable; at least, that there is such a peculiar ground for it as is not to be exemplified in any things natural or political among men (Works of John Owen, Justification, 5:209).