The intent of this question is not to define 'what is a true Christian?', but to ask:
Given that each tradition has it's own well-defined understanding of what being a Christian means, how do they explain how their own adherants can (after fitting that definition sufficiently to be regarded as members of their visible church) transgress commandments to an extant that is manifestly inconsistant with that definition and yet remain regarded as 'Christians' (i.e. they are not ex-communicated for their behaviour).
Particularly, how would they explain such situations in the light of:
1 John 2:4, "The one who says, “I have come to know Him,” and does not keep His commandments, is a liar, and the truth is not in him."
The answer sought is a short over-view from the perspective of different Traditions clearly identifying which perspective is in view and how it relates to the issue. Views are sought particularly from those tagged, but not necessarily limited to such.