Hm, being born in a stalinist country I definitely encountered more of the Stalinisit interpretations and ideology and they are definitely religion like.

But I also did met various other marxists and I did read some of Marx books, or rather some pages.

And I do remember him speaking of the utopian future. And also the part where he thinks, concentration camps for the enemies of the proletariat (everyone who does not want to have his property taken) will likely be necessary.

So gulags would not be a Stalin invention then.

(I think I read that in some of the letter exchanges with Engels, will look up)