Hey brother Dan, you asked the following questions...

What if some of us feel the Lord's calling to leave their secular calling and enter the full-time mission field? Would we support them, or assume they think they are better than the rest of us? What about holiness? What of those who feel the need to a greater separation from the world? Are we threatened or inspired by this?

For me, I think that the answer is "it depends". Like everything else in Christianity, I think that we have to look to Christ for the answer. If someone is truly convicted of their sin and seek to live more righteously in response to the free gift of salvation then not only will I support them with encouragement but perhaps even possibly with financial support as necessary (e.g. mission work). Sadly, however, I find that such feelings are often driven by monastic thought based on a need for self-righteousness. Back in the 2000's, I spent much time engaging with my fellow Christians at work in a forum much like this. At the time, the company was providing high levels of income for many of its employees, to the point where retiring within 5-10 years was within reach of at least some of those who worked there. I remember reading posts from my brothers and sisters in Christ that would go something like, "I plan to make as much money as I can so that I can go into ministry later." This is perhaps the worst outlook that I can imagine for a Christian because they devalue the ministry that "normal" people have in their community while simultaneously decoupling themselves from the support and accountability to the body of Christ. One friend of mine went down this path only to squander everything that he had saved and return a few years later. He admitted his embarrassment to me, though in retrospect it was probably the best thing that could happen to him.

I can share a similar story of friends who had little financially and gave up what they had to become Bible translators in Africa. When they asked me for financial support I asked what the husband would be doing for the organization. I did not get a clear response. We offered support regardless but placed a time limit on our giving to allow them time to figure things out. Now several years have passed and I still don't know what he does other than being some kind of "coordinator". And when their family comes to town on break every few years, the time with them is spent raising funds. Although I can't say with certainty that they are in the field for purely monastic reasons, I certainly see evidence of such. Not a single communication doesn't include words to the effect of "we are missionaries in Africa doing Bible translation". It's as though their identity in Christ is completely lost in the work that they are doing.

So I guess my question back to you, dear brother, is whether we are doing the right thing by supporting our fellow Christians in their pursuit of self-righteousness. Should we not instead be decoupling any sense of pride and self-worth that believers gain from their work? Whether you work for an hour feeding the homeless at a soup kitchen, or move your family halfway around the world to share the Gospel, everything you do should be done for God's glory and reign (kingdom). To do otherwise would be to place a burden on God such that, at the time of judgment, He owes you something for your good works.