"This one and firm rock, which we call the doctrine of justification", insisted Martin Luther, "is the chief article of the whole Christian doctrine, which comprehends the understanding of all godliness." He also called this doctrine the "articulus stantis et cadentis ecclesiae" ("article of the standing and falling of the church"): "…if this article stands, the Church stands; if it falls, the Church falls." Lutherans follow Luther in this when they call this doctrine "the material principle" of theology in relation to the Bible, which is "the formal principle." They believe justification by grace alone through faith alone in Christ's righteousness alone is the gospel, the core of the Christian faith around which all other Christian doctrines are centered and based.