I heard another accusation today about Amillennialism that actually is a new one on me.

The following is basically my attempt to give the gist of what was said. I think I am giving a correct understanding.
That Amillenniallism has its roots in Platonism (philosophically) and Gnosticism (theologically).
Among the claims they made is that although the early Church eventually responded to heresy by forming doctrines such as the Trinity; they did not get rid of the influence of Gnosticism in their eschatology. They claim that Gnosticism’s influence put too much on the spiritual rather than the physical. Saying that the physical (Earth) is bad and the spiritual (heaven) is good.
At this point, I do not intend to answer them. Rather, I would like to understand the issue better. I thought the Highway would be a great resource for that.
If you know of something that would help on that front, I would appreciate your input.