No church can confer Christianity on a single soul. It is completely between the individual and Christ. (”there is one mediator between God and man; the man Christ Jesus.”)
Yes. You said that earlier. But looking at Buck's question (it is his question so maybe he would like to review my interpretation) I understand it as asking whether a faithful, by adhering to the tenents of the Catholic Church has a basis for declaring himself a Christian. There must be some rational basis. For example, if a person went around declaring himself a Christian but stated that his belief that Jesus Christ was a mere mortal heretic and never peformed the miracles in the Bible could that person actually self-determine himself to be a Christian?