That might be a very difficult delineation to make, considering that
most of us are "professionals" in only one aspect of science or
technology and "amateurs" in all others.
I'm reminded of Alfred Wegener, the author of the theory of plate
tectonics, whom some did not consider a "real" geologist because he did
not have a degree in geology. Or Edward Lorenz, whose early formulations
of chaos theory were dismissed by physicists because Lorenz was not a
physicist.
The foregoing is not intended to be a denial of the advantage and
authority of formal training and practice in a given field, but a
cautionary note about drawing distinctions based solely on imputed
"professional" or "amateur" status. This is particularly true when we
delve into matters of theology (as we often do), where few of us are
"professionals."
Wil Milan