For some traditional Christians, Paul is everything (at least, a particular reading of Paul is everything), and the kingdom of God (on earth as in heaven!) is nothing, or next to nothing. The dangerous possibility that Jesus might want us to do things and thereby justify ourselves by our works has led generations of cross-centered Protestants to be very wary of the Gospels with their detailed kingdom agenda and kingdom ethic. Think of the sheep and the goats in Matthew 25: Is "eternal life" and its horrid alternative really to be decided by what people do? Thus, in many churches the canonical Gospels, or rather their dismembered fragments, are relentlessly translated into narratives which are "really" about Jesus' salvific death. This of course is not a complete travesty, since the Evangelists do indeed recount many of the incidents in Jesus' public career in such a way as to point forward to Calvary. But the strong tendency in this cross-centered reading of the Gospels is to ignore, for instance, Jesus' bracing Jubilee agenda in Luke 4, or the striking commands about hospitality to strangers in Luke 14, or the cup of cold water in Mark 10, or (again) the "inasmuch" of the sheep and the goats in Matthew 25.
N.T. Wright, "Whence and Whither Historical Jesus Studies in the Life of the Church?" in Jesus, Paul and the People of God: A Theological Dialogue with N. T. Wright, eds. Nicholas Perrin; Richard B. Hays.(p. 140). Kindle Edition.