A genuine Christianity is not pluriform, it does not have multitudinous realities at its core. It is not a cluster of beliefs that likeminded people rally around. A genuine Christianity—its inner reality—is in fact a person; it is God for us in the vicarious humanity of Jesus Christ. When people exit or walk away from this or that perceived form or expression of the “Christian existence,” they aren’t walking away from Christianity’s inner reality, per se, if in fact they believe that to be exhaustively represented in the form of that, as they have come to experience that, in this or that Christian tradition. In other words, if someone believes, when they walk away from Christianity, that they have done so by walking away from their immediate experience of that, they are sorely in error; and in error, in such a way that it potentially could have, or will have eternal consequences.
There are certainly damaging and erroneous forms or expressions of a self-proclaimed Christianity, but much of those are simply socio-cultural constructs masquerading as THE form of Christianity; at least in the way that it is presented to and received by its adherents. If someone has a personal relationship with the living God in Christ, walking away from Christianity becomes a much different thing than walking away from an experience of a so-called Christianity.
Make sure, if and when you walk away from something, you know what in fact you are walking away from. And just as important, make sure you understand what you are walking into as an alternative.