Commenting on Ephesians 5:
‘We are members of [Christ’s] body. “For this reason a man will leave his father and mother and be joined to his wife, and the two will become one flesh”’ (vv. 30–31). Christ’s union with the church as his body is the reason why a man should become one flesh with his wife. It is the heavenly marriage that warrants and dignifies an earthly marriage. In Paul’s reasoning, therefore, human marriage is not the reality for which Christ and the church provide a sermonic illustration, but the reverse. Human marriage is the earthly type, pointing towards the spiritual reality. This being so, the privilege of a Christian married couple is to declare the ‘great mystery’ (v. 32) by incarnating in their own marriage sacrificial divine love wedded to joyful human reverence (v. 33).
[from the New Dictionary of Biblical Theology entry on marriage; emphasis mine]