And to some extent, the claim that Man alone could not be saved was a claim of expedience, based on what worked best from the point of view of the growth and power of the church institution.
Yet, we must take seriously the possibility that this was in fact necessary for the survival of Christianity in a world where such claims were probably inevitable, given the way that Men's minds worked and the conditions of the time.
In a practical sense, it was correct that there was no salvation outside of the church in the medieval period; in that anybody outside the medieval church would not have been a Christian at all.
Not because it was 'impossible' to be a non-church Christian in a 'theoretical' sense; but that Men were not at that time fully independent agents, and were always part of some community from-which they (more passively and unconsciously than now) absorbed their faith.
For a medieval man to leave the community of faith (church) was therefore to leave the faith; and not to be in a community of faith was not to believe.
In other words, there has been an evolutionary development of human consciousness in the direction of greater autonomy and agency; and the nature of Christian life has been transformed by this.
We now must Now consciously choose to do (and think) much that was once unconsciously and passively done and thought.
Conversely, the kind of communal life that was once necessary and inevitable has become impossible and undesirable.