It's because most of CF is dedicated to theologians who got their degree from Wikipedia discussing and rehashing the same 10 to 20 topics in various boards:
>Calvinism
>Eliminating cognitive dissonance over not celebrating Sunday anymore
>The Trinity and how Jesus is God
>The latest moral outrage (in the news)
>Something Paul said that Peter or James could probably have said more clearly
Other significant parts of the site are LDS, JWs, Muslims, and non-Christians who want us to know they don't agree with us, as well as to agree occasionally with each other. Their topics include:
>Hell, Hades, Sheol, and Heaven
>The early Church
>How Jesus isn't really God
>How the Bible contains errors and the Quaran doesn't
>occasionally, atheism
A while back, there was an influx of non-Christians all over the place. Don't know what happened to that.
Anyway, this leaves the Games area, where people seem to go and disappear once in a while, and the "social" forums. The social forums (such as the one you're in) generally include about 10 different topics, which get reborn every few months:
>masturbation and/or pornography
>random thread game which fails
>latest moral outrage
>men vs women, or complimentarianism vs egalitarianism
>masturbation again
Most people go to other forums to post mostly anything, and come to CF for one or two "special" things. It's a shame.
Tl;dr - It's quiet because nobody comes here anymore.