Third, and most importantly, by focusing on the cross Luther picks up on the Pauline notion of the cross as the revelation of God’s purposes and as the criterion for truth in theology and church life.   This last point is arguably his most important and original contribution to the doctrine of the church.  It connects to his understanding of revelation, of the gospel, and of the church’s embodiment of those two things prior to the Second Coming and the Final Judgment.

As the church in the West faces social marginalization unknown for over 1500 years, the question of the marks of the church, those identifying features which she possesses, is likely to become more pressing.  Standard Reformed approaches tend to offer three marks: Word truly preached, sacraments properly administered, and church discipline correctly applied.  There was always some flexibility within the Reformed tradition on these points.  Calvin argued for only two explicit marks, Word and sacraments, while the Westminster Assembly put worship in the place of discipline.  Luther, however, offered seven: 1. The Word, 2. Baptism, 3. Eucharist, 4. The keys exercised publicly, 5. Ordained ministry, 6. Prayer, public praise, and thanksgiving to God, 7. The possession of the sacred cross.

We can, of course, see points of fundamental overlap between Luther and the Reformed here (e.g., Word is primary), and also reduce his number by counting baptism and eucharist as one.  Where he makes his major contribution is in the final point, possession of the sacred cross.

By making possession of the sacred cross into a mark of the church,  Luther does three things.  First, he offers a polemical counterpoint to the Roman Catholic cult of relics, at the centre of which lay pieces of the true cross and vials of Christ’s blood.  Justification by grace through faith has no need of such things.  Second, he connects his view of the true church to the standard idea of the trail of blood, whereby outward persecution validated the truth of the church’s testimony, given that darkness will always persecute light. This is why martyrologies such as those of Foxe were so important at the Reformation.  They offered an answer, albeit simplistic and often tendentious, to the question of where the church had been between ca. 500 and ca. 1500.   Third, and most importantly, by focusing on the cross Luther picks up on the Pauline notion of the cross as the revelation of God’s purposes and as the criterion for truth in theology and church life.   This last point is arguably his most important and original contribution to the doctrine of the church.  It connects to his understanding of revelation, of the gospel, and of the church’s embodiment of those two things prior to the Second Coming and the Final Judgment.

Paul’s teaching on the cross in 1Corinthians and on the church in 2Corinthians points to the fact that the kingdom is by its very nature currently hidden under suffering and contradiction.  That ought not to be a source of despair for the believer, for God’s power is actually manifested in and through such weakness.   By picking up on this Pauline note and making it into a mark of the true church, Luther surely adds a dimension to our understanding of ecclesiology which standard Reformed taxonomies missed. It is also one that we should recapture, for by placing weakness in its proper theological and ecclesiological context, it provides a frame of reference for understanding the difficulties which the church now faces and is likely to face with increasing frequency and intensity for the foreseeable future.  For Luther, as for Paul, the church reflects the cross: power made perfect in weakness.  And, like the cross, the church thus reveals those who are being saved (they who understand her weakness) and those who are perishing (they who despise her because of her weakness).

Carl Trueman is professor of historical theology and Paul Woolley chair of church history at Westminster Theological Seminary in Philadelphia, Pennsylvania. This article is taken from his blog and is used with permission.