Of course it is not just Christians who do this. A lot of groups trying to influence others to join them can be found saying similar things as a tactic for distancing themselves from appalling or embarrassing members of their group who do things they don’t approve of. We will just representatively use Christians for specificity and because they’re the ones most often saying this to me and I would like a handy reply I can point them to. (Hello there, Christian reading this because I linked you here! Have a seat! Make yourself comfortable!)
There are some good things I think that Christians are aiming at when they say “That’s not a real Christian” and yet some really problematic things too.
Before we explore both we need to make some huge, important distinctions. With all groups that are built around beliefs and values there is a difference between the real world thoughts and practices, historically, contemporarily, and across the individual members and observable subgroups of the overall group–both historically and contemporarily. According to the Pew Research Religion and Public Life Project, there are presently around 41,000 different Christian denominations worldwide. And not only have there been many more Christian sects over the previous 2,000 years of the religion’s existence, but even the denominations that exist today have taken substantially different forms of believing, behaving, worshipping, and judging as they have existed in any number of different times and places. If we are being merely descriptive, the Christian church historically has comprised billions of people. And Christians, even on the account of most forms of Christianity I am familiar with, are imperfect people. And so not only can their beliefs and values differ widely, but their behavior in any given instance might often not even live up to their own standards, according to their own interpretations of their faith.
Maybe some Christians want to claim that Christianity is only for perfect people or people who agree with them perfectly, such that any Christian who, on their perception, does something wrong should not be called a Christian. But that’s not for an outsider to decide. We can, quite fairly, say anyone who believes some minimum constellation of identifiably Christian things and self-identifies as a Christian qualifies to be considered a possible permutation of a Christian.
Now, the other thing someone might be saying when they say someone behaving or thinking immorally is not actually a Christian is that they do not represent the ideal values or beliefs that Christianity should be understood as teaching. This could mean several things, but I think each of them has a claim something like the following at its core: “Christianity, when rightly understood, does not teach people to believe or value in the ways this person does, therefore the faith should not be assessed as false or bad on account of this person’s behavior. Since a right understanding of the faith does not teach people to act in this way, it should not be rejected on account of people who act in this way.”
This claim about the “right” interpretation of the faith might be interpreted one of (at least) two ways. On the one hand, it might be an attempt to say not only that this is the right interpretation of the faith but it is the one usually promulgated or, at least, the one consistently taught by those churches with true claim to be Christian, etc. On the other hand, reformers might acknowledge that something they’re saying should be understood to be a Christian belief or value judgment historically has failed to be recognized by the church but nonetheless clearly can now be seen to be given what we have since learned.
Since traditions are living things, I have no problem in principle with people wanting to argue for better, more humane, more rational understandings of their faith, which take into account modern realities, modern learning, and advances in moral values. While I reject faith-based believing in principle, if someone is going to be a part of a faith, it is always far preferable to me that their beliefs at least be interpreted in a way that is more consistent with reality and with objectively defensible good than not...
Dan Fincke has his PhD in philosophy from Fordham University and is an adjunct assistant philosophy professor at Hofstra University and an adjunct philosophy professor at City College of New York (CUNY).