Early humanists saw no conflict between reason and their Christian faith (see Christian Humanism). They inveighed against the abuses of the Church, but not against the Church itself, much less against religion. For them, the word "secular" carried no connotations of disbelief that would come later, in the nineteenth century. In the Renaissance to be secular meant simply to be in the world rather than in a monastery. Petrarch frequently admitted that his brother Gherardo's life as a Carthusian monk was superior to his own (although Petrarch himself was in Minor Orders and was employed by the Church all his life). He hoped that he could do some good by winning earthly glory and praising virtue, inferior though that might be to a life devoted solely to prayer. By embracing a non-theistic philosophic base, however, the methods of the humanists, combined with their eloquence, would ultimately have a corrosive effect on established authority.
What phrase that has come to be associated with a lack of faith was not seen as an issue for Christians?
secular

Research since reveals self-examination beginning early in adolescence, but identity achievement rarely occurring before age 18. The freshman year of college influences identity development significantly, but may actually prolong psychosocial moratorium by encouraging reexamination of previous commitments and further exploration of alternate possibilities without encouraging resolution. For the most part, evidence has supported Erikson's stages: each correlates with the personality traits he originally predicted. Studies also confirm the impermanence of the stages; there is no final endpoint in identity development.
Evidence has supported which theorist's idea concerning stages of development?
Erikson

Overall, however, Whitehead's influence is very difficult to characterize. In English-speaking countries, his primary works are little-studied outside of Claremont and a select number of liberal graduate-level theology and philosophy programs. Outside of these circles his influence is relatively small and diffuse, and has tended to come chiefly through the work of his students and admirers rather than Whitehead himself. For instance, Whitehead was a teacher and long-time friend and collaborator of Bertrand Russell, and he also taught and supervised the dissertation of Willard Van Orman Quine, both of whom are important figures in analytic philosophy the dominant strain of philosophy in English-speaking countries in the 20th century. Whitehead has also had high-profile admirers in the continental tradition, such as French post-structuralist philosopher Gilles Deleuze, who once dryly remarked of Whitehead that "he stands provisionally as the last great Anglo-American philosopher before Wittgenstein's disciples spread their misty confusion, sufficiency, and terror." French sociologist and anthropologist Bruno Latour even went so far as to call Whitehead "the greatest philosopher of the 20th century."
Where has interest outside of those areas mainly come from?
through the work of his students and admirers rather