The ones *I* have personally conversed with, are ALL found on this very forum. I've never met one in real-life (thank goodness, I'll add).
Oh ... this is where I first encountered the reemergence of Flat Eartherism also. But, eventually, I sought answers for this beyond the Christian Forums.
The ones *I* have spoken with, sooner or later pulled out their bibles and at the very least demonstrated being extremely dogmatic and fundamentalistic in their bible beliefs (regardless of christian majority vote about what the bible says or doesn't say about flat/round earth - it does not matter to my point).
Even here at Christian Forums, ... my experience has been different. Flat Earth discussions I've participated in ... have dealt with issues of sunrise/sunset, gravity, density, seasons, the Coriolis Effect, refraction of light, evidence(s) of (non)-curvature, airflight times, GPS, ships going over the horizon, the fluidity of water, shadows on the moon, tides, perceptions of the horizon, eclipses, etc.
And, given that this is the Christian Forums, every now and then, someone will assert that the Bible supports Flat Earth belief. But, as I alluded to previously, those discussions don't last long, in part, because they're so easy to refute.
But off course, I'ld think it's to be expected that IF you come accross a flat-earther on a site called "christian forums", chances are rather big that that person is going to be a fundamentalist christian of some sorts.
Or, more generally, ... a christian, yes ..
If you log in on the forum and see a thread of which the subject clearly shows it's a defence of a flat earth and it is posted by a username you haven't seen before....
Are you really going to tell me that the chances of that person being an atheist vs being a christian (or claiming to be christian, if that makes you feel better) is 50/50?
I would agree with you that the very limited community of Atheists on Christian Forums ... are not likely to be supportive of Flat Earth belief.
But ... you are still dealing with a very limited sampling of true believers (i.e. here on Christian Forums). If you widen your scope beyond these forums, I would wager that you might find things to be somewhat different.
Also, it wasn't my claim that the proponents of Flat Earth are particularly Atheist, ... it's more that they are fairly irreligious in their presentation.