'Christian' has a rather large range of interpretations - here are some of them, and the reasons they have been refuted.
Christian has been used to refer to anyone who incorporates Christ into their religion. Thus Mormans, JWs and even Hari Krishnas call/have called themselves Christian. For differing interpretations about Christs role in relation to God, however, people that would call themselves mainstream Christians would not call these other groups Christians. Christian based sects, perhaps
Christian is used for anyone who adheres to the Christian religion. ie, believe in the centrality of Christ, recognise the concpet of the trinity, and give some sort of authority to the scriptures. Or they simply go to a church that deos these things. Or just go to a church. This is where it becomes hazy.
Is a Christian defined through adherence to a series of rules, rituals, traditions, and creeds, or defined by a personal faith?
Historically, this is the cause of the Protestant/Catholic split. Other doctrinal issues are involved, of course, but these were the basic reasons for the reformation.
Thus in modern times, both Catholics and Protestants view the others versions of Christianity with suspicion.
There are real Christians in both, and frauds in both. It comes down, as Stapel suggested above, to whether someone ultimately practices what they preach. Whether you see that around will largely depend on the society you live in.
