So I dug into this a bit further to find out why he was tweeting about Moloch (the tweet you've linked was a year ago). This was in relation to the Florida school shooting. He was pushing the idea that Trump, the NRA and the GOP are a death cult sacrificing kids via school shootings. Such as this one:

"I hope every one rembers right now - only issues that matter are defeating GOP death cult at ballots - & removing a treasonous - criminaly deranged serial sexual assaulting Nazi pimp nra blood whore from office before he can do more damage - everything else is just noise."

And this one where he links this 2012 NY Review of Books article claiming guns are Moloch, which in part reads:

"The gun is our Moloch. We sacrifice children to him daily—sometimes, as at Sandy Hook, by directly throwing them into the fire-hose of bullets from our protected private killing machines, sometimes by blighting our children’s lives by the death of a parent, a schoolmate, a teacher, a protector. Sometimes this is done by mass killings (eight this year), sometimes by private offerings to the god (thousands this year).

The gun is not a mere tool, a bit of technology, a political issue, a point of debate. It is an object of reverence. Devotion to it precludes interruption with the sacrifices it entails. Like most gods, it does what it will, and cannot be questioned. Its acolytes think it is capable only of good things. It guarantees life and safety and freedom. It even guarantees law. Law grows from it. Then how can law question it? Its power to do good is matched by its incapacity to do anything wrong. It cannot kill. Thwarting the god is what kills. If it seems to kill, that is only because the god’s bottomless appetite for death has not been adequately fed."

Here is what Twitter came up with for his tweets between 2/14/2018 and 2/20/2018. Weirdly, it doesn't list either the Moloch one, or the Mooloch tweet, but you can see him harping on the topic over multiple different tweets for several days.

Hannity called him out on it. Which led to a Twitter war between the two, though apparently Hannity removed his tweet.

TL;DR: Cusak is painting gun rights people as part of a child sacrifice cult. Alinsky, much?