A friend described a change in the Christians he has been studying with over the years. He noted that early on, they stressed that if a Christian was not focused on being a disciple, they weren't really getting it right. There really isn't any other kind of Christian other than one who is trying to be a disciple. Now, a group with large overlap with the first is defining their Christianity in terms of cultural-political ideas, which he described as "woke" politics, though they would certainly describe it differently. In their current definition, unless one is pursuing justice, one is not really a Christian at all, but only some sort of hanger-on going through the motions, oblivious to the Jesus truth. That idea is ascendant in the denominational churches at present.
My first thought was that there is a type of person that discerns inadequacy and incompleteness in the Church at large and leaps to conclusions about what causes that and what the solution is. That may be based on their own journey, which they are projecting is necessary for other Christians as well, or it may stem from an unfortunate willingness to judge others. My friend acknowledged that such might be true, but was not entirely excited by my analysis. Fair enough.
But into my mind popped another thought from the early days of my Christian reading. I was given a book in the 1970s about Christian community that asserted that this was not optional. There might be many ways that Christians could live in community with each other - and in true 1970s fashion thought that exciting new models were being experimented with that might transform the church(!!) - but that most importantly, there is no other way to live in Christ other than to live in some sort of community. The thought of that has always haunted me, and I have kept the primacy of the community in Christian walk in front of me, even as I wondered if I were being half-hearted about such commitment. From about 1975 - 1985 we were in constant discussion with Christian friends about whether we should buy property together and live near each other in deeper levels of sharing and intimacy. Nothing ever came of that, though much of that group remain our closest friends, with whom we still meet regularly. After having been in many separate churches over the years most of us are in the same congregation now, including some of our grown children. (A different church than any of us started in or even knew anything about then.)
Once that seal had been broken, I thought of the other Christians I have known and read about over the decades and what their opinions were on the non-optional parts of Christian expression. I certainly knew many in the 80s and 90s who considered conservative politics, or some cultural emphasis derived from that to be essential obligation for any active Christian. Not that political volunteering or advocacy was required, but that there were Christian values under assault, and the political right, with all its faults, was at least with us on trying to preserve some things. A subset of this is the group that is devoted to Christian schooling and home schools. We were in a congregation that had many foreign adoptees, went on foreign missions, and tried very hard to keep contact with immigrant and refugee communities. A few years ago I dropped by the website of a church I previously attended and read a lesson by the pastor that "non-violence is the heart of the Gospel." (I cynically believe that liberal denominational pastors being what they are, he has moved to the current fashion of racial justice being the center of the gospel, and that he could artfully explain to me why it's exactly the same thing.) The idea that the absence of war is very near to the ultimate work of the church has never been far from the surface through most of my life.
I don't think any of those answers is wrong. There may be a seriousness that is not optional that expresses in many ways but is interconnected. There may be Many Only kinds of Christian, but they might be the same. Yet I think that is too easy an answer, giving too much credit to us all. More likely, we are all quite dim in perceiving what the center is, but remain arrogant enough to make pronouncements to others.