believing, committed, devout, faithful, good, practising/practicing, professing
Boyle was a devout Christian and an enthusiastic student of the Bible.

born-again, evangelical, fundamentalist
He became a born-again Christian at 40 and turned his back on his misspent youth.

Orthodox, Protestant, etc.
conservative, liberal, right-wing

be brought up (as), be raised (as)

believe
pray, worship

Christian is used with these nouns:
background, belief, believer, burial, calendar, charity, church, civilization, college, community, conception, congregation, conservative, context, conversion, conviction, doctrine, dogma, duty, education, era, ethics, extremist, festival, god, gospel, holiday, leader, leadership, love, marriage, martyr, meditation, message, minister, ministry, minority, mission, monk, moral, morality, myth, name, nation, orthodoxy, philosopher, philosophy, prayer, preacher, principle, right, saint, school, scripture, sect, symbol, symbolism, teaching, theology, thinker, thought, tradition, unity, value, view, virtue, vocation, worship, writer