In a recent post, I began by unpacking the Apostle Paul’s idea from Ephesians 5 that human marriage is a ‘living parable’ of the spiritual marriage of Christ to His church. Paul argues there in Ephesians 5 that the ‘one flesh’ passage of Genesis 2:24 is primarily about Christ and His church. God created human marriage for humans to understand the Gospel relationship between Christ and those He came to save from their sins.

But what does this have to do with sexuality? The answer lies specifically in the theological doctrine of union with Christ. The Apostle Paul considers this concept of believers being united with Christ as fundamental to the truth of the Gospel. As Christ is crucified, my old sinful self is crucified; as Christ is raised, I am raised; as Christ is glorified, I too will be glorified. Christ’s righteousness is my righteousness because I have been united with Him. Believers in Jesus Christ are spiritually united with Him. We are spiritually one with Him, which is why Paul uses Genesis 2:24 to speak of this spiritual marriage or relationship. We have become “one flesh,” or “one body” with Christ.

But how do we demonstrate this mystical spiritual union with Christ? In the New Testament church we have two such ways that we refer to as sacraments or ordinances: the Lord’s Supper and Baptism. The Apostle Paul draws the connection between baptism and union with Christ in Romans 6:3-5: “Or don’t you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. ⁵For if we have been united with him in a death like his, we will certainly also be united with him in a resurrection like his.” Paul links the act of baptism with spiritual union. We were baptized into Christ.

The same is true of the Lord’s Supper. In John 6:33-26 Jesus says “Very truly I tell you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you.⁵⁴ Whoever eats my flesh and drinks my blood has eternal life, and I will raise them up at the last day. ⁵⁵ For my flesh is real food and my blood is real drink. ⁵⁶ Whoever eats my flesh and drinks my blood remains in me, and I in them.” Verse 56 is key as the eating of Christ’s body and drinking His blood is a clear reference to the Lord’s Supper, established later in Christ’s ministry. Christ Himself links the Lord’s Supper with spiritual union with Him, He remaining in us and we in Him. The Apostle Paul picks up this theme as well in 1 Corinthians 11, but there Paul gives a warning that is crucial to our discussion.

The sacraments/ordinances instituted by Christ are only for those who are indeed one with Him. Paul makes this explicit in 1 Corinthians 11 when he states that there is a judgment that comes from eating and drinking in the Lord’s Supper without discerning what the Lord’s Supper symbolizes. The Lord’s Supper is a symbol of oneness, of communion with Christ in His death on the cross, and is therefore only for those who are indeed one with Christ and actually in spiritual union with Him. Paul even states that members of the Corinthian church died for taking the Lord’s Supper improperly. There is a judgment for those who come to the Lord’s Table and proclaim that they are one with Christ when indeed they are not. In essence, they are abusing the communal supper of God’s people by pretending to be one when they are outside of fellowship with Christ. They participate in the sign, but miss that which is signifies.

In marriage, we see this same idea of mystical union of two people into one. As two individuals come together, with the husband and wife leaving their parents and ‘cleaving’ to each other, they become one through a marriage covenant. They then demonstrate this mystical covenant oneness physical into the act of sexuality. Just as we demonstrate our oneness as believers with Christ through the physical acts of baptism and the Lord’s Supper, we demonstrate our oneness with our marriage partners through the physical act of sexuality. As our human marriages find their source in the spiritual image of Christ, in many ways, our physical demonstrations of that oneness find their source in the physical demonstrations of our oneness with Christ. Just as the Lord’s Supper is very much a covenant renewal ceremony, in many ways the act of sexuality is renewal of the marriage covenant.

The issue in today’s world is that we have divided the act of sexuality from what is signifies. This is not a new problem. Paul asks in 1 Corinthians 6:16 “Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, “The two will become one flesh.” When we engage in extra-marital sexual activity, we are lying to ourselves, our sexual partner, or whoever else may know. We are participating in an act that declares oneness where there is none!

If human marriage and gender find their origin in the relationship between Christ and the Church, and the act of sexuality is the physical demonstration of that marital oneness, then sexuality itself is linked with the relationship between Christ and the Church. Just as the church physically demonstrates its union with Christ, and must do so properly and truthfully discerning the body and death of Christ, so too sexuality demonstrates union with our spouse, and we must do so properly within that covenant relationship or find ourselves in opposition to the created order of God and justly deserving His displeasure.