By late 4th century AD, the raw transformative power of the Gospel was already in deep decline. The way of Christ was being supplanted by the Constantinian institutional Christianity. Since the tangible power of God was not widely demonstrable, something else was bound the take its place. That “something else” was forensic, legally focused Christianity. In redefining the overarching meta-narrative of the New Covenant as being exclusively a legal matter, the practical power of the Gospel was theologically legitimized. Institutional Christianity became a purveyor of solutions which were purely speculative, experientially unverifiable, and requiring one to die before the veracity of their theories could be personally ascertained. In other world – that so-called gospel was not much use for the for the living. It was only useful for the dead.
Historically, here’s how things got to where they did. In 410 AD Rome was sacked by Visigoths. At that time, Rome was viewed as the mother city of Christianity, and it came as a huge shock to the Western world that their relatively newly adopted religion – Christianity – was powerless to stop that sacking by pagan barbarians. In response, in mid-420s AD Augustine penned his opus magnum “The City of God”. In that volume he made important doctrinal corrections, but committed probably just as many worldview errors as he sought to correct. In trying to salvage Christianity from its alleged failed responsibility to protect Rome, he simply relegated everything that can be expected of God to the realm he called “the city of God” which can be accessed only after death.