Richard Fletcher [The Barbarian Conversion] notes that ancient Christendom was not monolithic:
In terms of custom and practice there were many churches in sixth- and seventh-century Europe, not One Church. Christendom was many-mansioned.
Fletcher talks about the motif of exile in the monastic expansion. Christians, following the writing of Augustine, saw themselves as exiles and pilgrims and then the monastics took this exile literally. They often left their homeland and people to found monastic missions amongst others. Fletcher says:
Pilgrimage, in the sense of ascetic renunciation of homeland and kinsfolk, is of special importance in our understanding of the phenomenon of conversion in the early Middle Ages. Pilgrimage merged insensibly into mission. The monasteries that were founded by the exiled holy men had something of the character of mission stations. It was not that they were established primarily among pagans; indeed, they could not have been, dependent as they were on wealthy patrons, necessarily Christian…for their endowments…But their monastic communities were situated on the margins of Christendom, and had what might be called “diffusive potential” among nearby laity who were Christian only in the most nominal of senses.
It seems to me that we could apply this same method to the diffusion of the faith in our day. Establishing tightly-focused communities at the margins of our society, for example in rural areas and urban areas that aren’t glamorous. Communities devoted to Biblical saturation, mission and learning which could aim to gradually convert the surrounding area.