Prior to Marx, socialists used radicalized religion to hawk their poison.
By the mid 1800s, the world was littered with failed Utopian experiments that used various forms radicalized religion to bind adherents to the community.
The Young Hegelians (Marx, Feuerbach, etc.) realized that they could use radical anti-religion.
By building on anti-religion as a theme, they were able to attack the core of a free society while being able to dismiss the failures of Utopian societies as being caused by religion .;.. and not a fundamental fault of communitarianism.
Centuries after Feuerbach and Marx, we have a world in which many people associate socialism and anti-religion.
One odd danger we face is that the socialist left can very easily change theme and start pushing radicalized religion ... blaming the failures of socialism on its anti-religious nature.
The dichotomy:: "Should the socialist utopia be based on religion or anti-religion?" is a false dichotomy.
When people are drawn into a false dichotomy they will end up being pushed in directions they would otherwise not travel.
Sadly, many conservatives seem to be reacting to the Obama administration by taking a radical view of religion. A radicalization of religious can come back and hurt us as the forces of tyranny are skilled at using radical religion to harm society.