Westminster Project 8.7

Christ, in the work of mediation, acts according to both natures, by each nature doing that which is proper to itself. Yet by reason of the unity of the person, that which is proper to one nature is sometimes in Scripture attributed to name of the other nature.
(WCF 8.7)

As we come to the closing articles of the chapter exploring Christ’s role as mediator, the confession draws our attention to the kind of mediator we truly have right now in heaven.

First, as we have seen, the person of Jesus is both fully God and fully man. Simply put, Jesus is 100% God and 100% human (John 1:1-3, Colossians 1:19, Philippians 2:6-8). He had to be this way because He needed to redeem all that we are. Therefore, He did not merely appear human or pretend to be human—He truly was. Almighty God really took on flesh and was born of a virgin 2,000 years ago so that He could be the perfect Savior and mediator for His people (Hebrews 2:14-17, 1 Timothy 2:5-6; cf. Isaiah 43:11).

Now, without conflating Jesus’ two natures (monophysitism), nor separating them too far (Eutychianism), we must acknowledge that Jesus “by each nature did that which is proper to itself.” What does this mean? Without pushing it too far, when Jesus died on the cross, real blood was required to redeem people from their sins, and real suffering had to be endured under the curse—and it was the person of Christ who was able to do this because He is both very God and very man (Isaiah 53; cf. Hebrews 9:14, 1 Peter 3:18). 

Chad Van Dixhoorn writes, “What is important to say is that what is true of either nature of Christ is also true of the person of Christ. This is usually called ‘the communication of attributes.’ That is, what can be said of the humanity of Christ can be said of His person; what can be said of the divinity of Christ can be said of His person” (Confessing the Faith, p. 126).

In other words, we are not to separate or conflate the two natures of our Lord to the extent that He was walking around with two minds arguing with one another. Rather, there are real differences between the natures, and what each nature does can and must be credited to the one person of Christ.

The author of Scripture, the Holy Spirit, inspired certain writers to help us see this more clearly. Thus, Scripture sometimes highlights particular attributes of Christ’s person to remind us that He was neither merely man nor merely God—but very God and very man, both united in one person. For example, the Word became flesh and made His dwelling among us (John 1:14), yet He grew tired and hungry (Mark 11:12). This is not two people, but one person with two natures. Biblical writers emphasize one nature or the other depending on the moment. They do not seek to confuse us or conflate the two natures but simply to highlight one aspect over the other. Sometimes the humanity of Christ is expressed with divine language and vice versa (see Acts 20:28, 1 John 3:16).

Is this difficult to understand? Absolutely! We are exploring concepts far beyond our full comprehension. But one thing is made simple for all God’s people: we have broken God’s law in every way, and there was no chance on earth that we could fix it ourselves. So, in God’s love, kindness, and mercy, He became flesh, was tested in every way yet did not sin, so that He could go to the cross on behalf of His people and offer His life as the perfect sacrifice. That life was accepted; Christ was raised from the dead and ascended to heaven, where He now serves as the perfect mediator between humanity and God—of which He is both (Hebrews 4:14-16).